JP4614844B2 - Laser processing method and laser processing apparatus - Google Patents

Description

  The present invention relates to a laser processing method and a laser processing apparatus, and more particularly to a laser processing method and a laser processing apparatus for forming a hole in a workpiece by trepanning processing.

Trepanning is performed to form a hole having an opening larger than the beam spot of the laser beam. A conventional trepanning method will be described with reference to FIG. A circumferential track 51 is defined on the surface of the workpiece 50. On the trajectory 51, a plurality of target incident positions P _A , P _{B and the} like on which the laser beam is to be incident are arranged. The incident position of the laser beam on the work surface is moved by a galvano scanner.

First, the first target incident position P _A of the orbit 51, the galvanometer scanner is settled. After the setting is completed, the laser beam is incident on the first target incident position through the galvano scanner. Thus, holes H _A corresponding to the target incident position P _A is formed. Next, the target incident position is moved to the second target incident position P _B on the trajectory 51, and the galvano scanner is set. After completion of the setting, the laser beam is incident on the second target incident position P _B through the galvano scanner. Thus, holes H _B corresponding to the target incident position P _B is formed.

  As described above, the process of setting the galvano scanner at the target incident position on the trajectory 51 and allowing the laser beam to enter the target incident position through the galvano scanner after the completion of the setting is repeated a plurality of times. One hole larger than the beam spot is formed by partially overlapping the holes formed by the laser beams incident on the target incident positions.

  Next, a galvano scanner conventionally used for the above-described trepanning process or the like will be described with reference to FIG. The galvano scanner includes a first scanner 54 and a second scanner 55. The first scanner 54 moves the incident position of the laser beam on the processing surface in one direction, and the second scanner 55 moves the incident position of the laser beam on the processing surface by the first scanner 54. Move in a direction perpendicular to the direction. By combining the operations of both scanners, the incident position of the laser beam can be moved in a two-dimensional direction on the processing surface.

  The galvano scanner is controlled by a galvano control device (galvano driver) 53. The galvano controller 53 is controlled by the main controller 52. The main controller 52 includes a personal computer, for example. The galvano controller 53 includes an input interface 53a, a memory 53b, an output circuit 53c, and an arithmetic circuit 53d.

In trepanning method described with reference to FIG. 7, after entering the laser beam to the target incident position P _A, describing a target incident position control of the galvano scanner in the case of moving from P _A to P _B. Here, it referred to as a starting point the target incident position P _A, it is assumed that the target incident position P _B is referred to as the end point.

The main control device 52 sends position data corresponding to the end point P _B to the input interface 53 a of the galvano control device 53. In order to move the target incident position to the end point P _B, it is necessary to determine a route to the end point P _B. Route to the end point P _B is, so that the arithmetic circuit 53d into a predetermined shape (e.g., straight), the arithmetic circuit 53d, based on the position data of the end point P _B, the position data (route to route Position data of each point set to) is generated. This position data is referred to as route position data. Path position data for each control cycle (for example, 50 μs) is generated.

The route position data is stored in the memory 53b. For each control cycle, path position data is read from the memory 53b to the output circuit 53c. The output circuit 53c controls the first scanner 54 and the second scanner 55 based on the path position data, so that the target incident position moves to the end point P _B. After the galvano scanner is set to the end point P _B , the laser beam is incident on the surface to be processed. Such a galvano scanner is disclosed in Patent Document 1, for example.

JP 2002-196275 A

  A trepanning technique capable of forming high-quality holes is desired. In addition, a time-efficient trepanning technique is desired.

  An object of the present invention is to provide a laser processing method and a laser processing apparatus applicable to trepanning processing for forming a higher quality hole.

  Another object of the present invention is to provide a laser processing method and a laser processing apparatus applicable to time-efficient trepanning processing.

According to the first aspect of the present invention, when the target incident position is moved on the workpiece, the beam scanning is performed to scan the laser beam so that the laser beam incident position moves toward the moved target incident position. In a method of performing laser processing using a scanner, (a) a target incident position of the beam scanner at a start point on the trajectory of a workpiece on which a closed trajectory on which a laser beam is to be incident is defined on a surface; a step of moving, (b) while controlling the beam scanner so that the target incident position is moved starting the start point along said trajectory, said workpiece with a pulsed laser beam through said beam scanner to be incident on, the pulse laser beam mutually beam spot between successive pulses by overlap partially, the steps you irradiating the pulsed laser beam over the entire circumference of the track A laser processing method of repeating at least two times with different starting point in the step (a) is provided.

  According to the second aspect of the present invention, in step (b) of the laser processing method of the first aspect, the target incident position is moved along the trajectory without setting the beam scanner at each target incident position. A laser processing method is provided.

According to a third aspect of the present invention, a holding base for holding a workpiece in which a closed track on which a laser beam is to be incident is defined on a surface, a laser light source that emits a pulsed laser beam, and the laser light source When the pulse laser beam emitted from the laser beam is incident on the workpiece to be held on the holding table and the target incident position is input from the outside, the incident position of the pulse laser beam moves toward the target incident position. A beam scanner that scans a pulse laser beam, and a control device that controls the laser light source and provides a target incident position to the beam scanner, the control device comprising: (a) the workpiece to be processed; the position of the starting point on the trajectory, the process gives the beam scanner as a target incident position, and (b) to the target incident position is moved along said trajectory starting from the start point The while changing the target incident position given to the beam scanner, to emit a pulsed laser beam from the laser light source, a beam spot between successive pulses to one another of the pulse laser beam by overlapping partially, wherein a step wherein you irradiating the pulsed laser beam over the entire circumference of the track, the laser processing apparatus is provided to repeat at least two times with different starting point in the step (a).

  According to the fourth aspect of the present invention, in the step (b), the control device for the laser processing apparatus according to the third aspect moves along the trajectory without setting the beam scanner at each target incident position. A laser processing apparatus is provided for controlling the beam scanner to move the target incident position.

  The laser processing method according to the first aspect and the laser processing apparatus according to the third aspect repeat steps (a) and (b) at least twice with different starting points. For example, consider a case where the energy density of the incident laser beam is different between the vicinity of the start point and other sections of the portion on the orbit where the target incident position moves in step (b). In such a case, steps (a) and (b) are repeated twice or more with different starting points, so that the positions of the starting points are dispersed on the orbit, so that the energy density distribution in the circumferential direction of the orbit is made closer to the uniform. be able to. Thereby, improvement of processing quality is achieved.

  The laser processing method according to the second aspect and the laser processing apparatus according to the fourth aspect move the target incident position in step (b) without setting the beam scanner to each target incident position on the orbit. Time efficiency can be improved compared to laser processing in which a beam scanner is set at each target incident position on the orbit and a laser beam is incident on each target incident position.

  FIG. 1 schematically shows a laser processing apparatus according to an embodiment of the present invention. The laser light source 1 emits a pulse laser beam. The main controller 8 controls the laser light source 1 so that a pulse laser beam is emitted at a constant pulse period during a desired period.

  A pulsed laser beam emitted from the laser light source 1 is incident on the surface (surface to be processed) of the workpiece 6 through the galvano scanner 2 and the fθ lens 5. The holding table 7 holds the workpiece 6. An XY orthogonal coordinate system having an XY plane parallel to the surface to be processed and fixed to the fθ lens is defined.

  The galvano scanner 2 includes a first scanner 3 and a second scanner 4. The first scanner 3 includes a scanning mirror 3a and a swing mechanism 3b, and the second scanner 4 includes a scan mirror 4a and a swing mechanism 4b. The scanning mirrors 3a and 4a reflect the pulse laser beam, respectively. The swing mechanisms 3b and 4b swing the scanning mirrors 3a and 4a, respectively.

  By oscillating the scanning mirror 3a of the first scanner 3, the incident position of the pulse laser beam moves in the X direction on the surface to be processed. By oscillating the scanning mirror 4a of the second scanner 4, the incident position of the pulse laser beam moves in the Y direction on the surface to be processed. By combining the swinging motions of both scanning mirrors, the pulse laser beam can be moved in a two-dimensional direction on the surface to be processed. The galvano scanner 2 is controlled by a galvano control device (galvano driver) 9. The galvano controller 9 is controlled by the main controller 8.

  Next, the main controller 8 and the galvano controller 9 for controlling the galvano scanner 2 will be described in detail with reference to FIG. The main control device 8 includes, for example, a personal computer and has an arithmetic circuit 8a. The arithmetic circuit 8a is, for example, a central processing unit (CPU) of a personal computer. The galvano control device 9 includes an input interface 9a, a memory 9b, and an output circuit 9c. The input interface 9a is composed of, for example, a dual port random access memory (DPRAM).

  Consider a case where the galvano scanner 2 is controlled so that the laser beam is scanned along the trajectory from the start point to the end point of the trajectory defined on the processing surface. The arithmetic circuit 8a of the main control device 8 generates XY coordinate data (referred to as command incident position data) corresponding to each command incident position set between the start point and end point on the trajectory. The number of command incident positions set on the orbit is, for example, about 100. The command incident position data generated by the arithmetic circuit 8a of the main control device 8 is stored in the input interface 9a of the galvano control device 9, and further transferred to the memory 9b.

  The main control device 8 issues a movement command to the galvano control device 9. The movement command is issued after the XY coordinate data of all command incident positions set on the trajectory are input to the galvano controller 9. When the galvano control device 9 receives the movement command, it sends the command incident position data from the memory 9b to the output circuit 9c for each command incident position, for example, at a cycle of 50 μs.

  The output circuit 9c controls the swing mechanism 3b of the first scanner 3 and the swing mechanism 4b of the second scanner 4 based on the command incident position data transferred from the memory 9b. The position on the processing surface specified by the command incident position data transferred from the memory 9b to the output circuit 9c is referred to as a target incident position. In this way, the target incident position can be moved at every control cycle (for example, 50 μs) along the trajectory from the start point to the end point on the processing surface.

  A position on the processing surface on which the laser beam that has passed through the galvano scanner 2 is assumed to be incident is referred to as an actual incident position. When the target incident position moves on the processing surface, the laser beam is scanned so that the actual incident position moves toward the target incident position after the movement.

  In the main control device 8 and the galvano control device 9 of the embodiment, the arithmetic circuit 8a of the main control device 8 generates position data (position data of each point set on the route) that determines the route from the start point to the end point. To do. In a conventional galvano scanner, an arithmetic circuit included in a galvano control device generates position data that defines a route from a start point to an end point.

  The arithmetic circuit 8a included in the main control device 8 is, for example, a CPU of a personal computer. The CPU of the personal computer can perform calculation at a higher speed than the arithmetic circuit included in the galvano control device. For this reason, if the main controller 8 and the galvano controller 9 of the embodiment are used, the shape of the path from the start point to the end point can be made more complicated than the conventional one (for example, a straight line shape).

  The main control device 8 and the galvano control device 9 can be considered as a single control device, and this control device can be considered to control the galvano scanner 2.

  Next, a method for setting the galvano scanner 2 at a certain target incident position will be described with reference to FIG. The swing angle of the scanning mirror 3a is defined as a displacement angle from the reference posture of the scanning mirror 3a, and the swing angle of the scanning mirror 4a is defined as a displacement angle from the reference posture of the scanning mirror 4a. The swing angle of the scanning mirror 3a corresponds to the X coordinate of the actual incident position, and the swing angle of the scanning mirror 4a corresponds to the Y coordinate of the actual incident position.

The swing angles corresponding to the X and Y coordinates of the target incident position to be set are Q _x and Q _y , respectively. The swing angles Q _x and Q _y will be referred to as target swing angles Q _x and Q _y , respectively. The description of the X scanning mirror 3a will be continued.

3 shows the swing angle of the case of controlling the swing mechanism so that the target oscillating angle Q _x, the time variation of the oscillation angle of the scanning mirror 3a. In this example, the swinging angle of the front control is smaller than the target swing angle Q _x. Permissible range A of oscillation angle including the target swing angle Q _x are determined. In addition, a waiting time S for determining whether the scanning mirror 3a is set is determined.

When the swing angle is controlled to become the target swing angle Q _x , the swing angle increases and falls within the allowable range A at time t ₀ . Thereafter, the swing angle continues to increase, and reaches the target swing angle Q _x at a certain time. However, due to inertia or the like of the scanning mirror 3a, Yuradokaku continues to increase further, at time t ₁ deviates from the allowable range A. Thereafter, the swing angle is started to decline after increased up to a predetermined maximum value, reenters within the permissible range A at time t _2.

After entering into the time t ₂ again allowed range A, the swing angle continues to decrease, again reaches the target oscillating angle Q _x at a certain time. However, the swing angle continues to decrease due to the inertia of the scanning mirror 3a. The swing angle starts to increase after decreasing to a predetermined minimum value. This minimum value is within the allowable range A. Thus, the swing angle is close to the target swing angle Q _x while attenuating vibrations. Time t ₂ after the swing angle does not deviate from the permissible range A.

If the swing angle is within the allowable range A during the waiting time S from the time when it enters the allowable range A from outside the allowable range A, the scanning mirror 3a reaches the target swing angle (that is, the target incident position). Judge that it was settled. In this example, at time t ₃ when passed from time t ₂ only waiting time S, the scanning mirror 3a is determined to have been stabilized at the target swing angle Q _x.

  The X scanning mirror 3a has been described above, but the same applies to the Y scanning mirror 4a. By setting both the X scanning mirror 3a and the Y scanning 4a, the galvano scanner 2 is set.

Next, with reference to FIG. 4, the laser processing method proposed by the inventors of the present application and the problems resulting therefrom will be described. First, the laser processing method will be described. FIG. 4 is a plan view of the workpiece 6. On the work surface, circumferential closed trajectory T are defined, the start point P _s is disposed on the track T.

First, the starting point P _s, moves the target incident position, thereby settling the galvanometer scanner 2. Then, along the track T to around the target incident position from the start point P _s. In the example shown in FIG. 4, the target incident position is rotated clockwise as indicated by an arrow.

  The command incident position data is generated so that the target incident position circulates along the trajectory T at a constant angular velocity. During the period in which the target incident position is circulated, the waiting time S (see FIG. 3) until the galvano scanner 2 is set at each target incident position on the trajectory T is not ensured (the galvano scanner 2 is not set). Corresponding to the rotation of the target incident position, the actual incident position circulates substantially along the trajectory T.

  A pulsed laser beam is incident on the surface to be processed during the period in which the target incident position is circulating. The beam spot on the processing surface is, for example, circular. The pulse of the pulse laser beam is incident on the surface to be processed with a constant period. A position on the processing surface where the pulse laser beam is actually incident is referred to as a pulse incident position.

Simultaneously with the start of the movement of the target incident position, the incidence of the pulse laser beam is started. Prior to moving the start, since the galvanometer scanner 2 is stabilized at the starting point P _s, a pulse incident position of the first pulse of the pulse laser beam, substantially coincides with the start point P _s. The pulse incident positions P _{1 to} P _{10 of the} subsequent pulses are arranged on the trajectory of the actual incident position (substantially on the trajectory T). When pulse incident position reaches the end point P _10, and ends the incidence of the pulsed laser beam to the work surface, and the movement of the target incident position. In this example, the end point P ₁₀ of the pulse incident position is coincident with the start point P _s of pulse incident position.

  Note that the timing of movement of the target incident position by the galvano scanner 2 and the incident timing of the pulse laser beam do not need to be synchronized. In other words, the timing at which the galvano control device 9 controls the rocking mechanisms 3b and 4b and the timing at which the pulse of the pulse laser beam is emitted from the laser light source 1 do not have to be synchronized.

With the pulse laser beam, holes corresponding to each of the pulse incident positions P _s and P _{1 to} P ₁₀ are formed on the processing surface. In FIG. 4, circles centered on the respective pulse incident positions P _s and P _{1 to} P ₁₀ indicate hole openings corresponding to the respective pulse incident positions. When the openings of the holes corresponding to the respective pulse incident positions partially overlap each other, one hole larger than the beam spot (hereinafter referred to as a trepanning hole) is formed. The ratio of the radius of the trajectory T to the radius of the beam spot is selected so that the openings of the holes corresponding to the pulse incident positions partially overlap to form one hole.

  In this laser processing method, a trepanning hole is formed by allowing a laser beam to enter the surface to be processed through the galvano scanner 2 while rotating the target incident position along the trajectory T without setting the galvano scanner 2. Since the galvano scanner 2 is not set during the circulation, the time efficiency can be improved as compared with the conventional trepanning method that repeats the setting of the galvano scanner 2 during the rotation.

Next, problems caused by this laser processing method will be described. And from the starting point P _s along the track T, as the target incident position is moved at a constant angular velocity, the galvanometer controller 9 controls the galvanometer scanner 2. That is, it is desired to move the actual incident position along the trajectory T at an equal angular velocity. In order to move the actual incident position at a constant angular velocity, the scanning mirrors 3a and 4a need to be swung at a predetermined angular velocity.

However, before starting the movement of the actual incident position, galvano-scanner 2 is stabilized at the starting point P _s, the scanning mirrors 3a and 4a are both substantially stationary. Therefore, in practice, the moving angular velocity cannot be made equal to the angular velocity at the same time as the movement of the actual incident position starts (the moving angular velocity at the start of movement is almost zero). The moving angular velocity at the actual incident position becomes equal angular velocity after acceleration from the start of movement. A period during which the moving angular velocity at the actual incident position is accelerated is referred to as an acceleration period, and thereafter a period during which the moving angular velocity at the actual incident position is maintained at a constant angular velocity is referred to as a constant angular velocity period.

The pulse of the pulse laser beam is incident on the surface to be processed with a constant period. Therefore, the interval between the pulse incident positions closest to each other on the trajectory T (referred to as the pulse incident interval) becomes wider during the acceleration period with the increase in the moving angular velocity of the actual incident position, and the equiangular velocity period. The inside is constant. During the acceleration period, in particular, immediately after the start of movement of the actual incident position (i.e., in the vicinity of the starting point P _s), the moving velocity than during constant velocity period is slow, the pulse incident spacing is narrow.

The overlap between the pulse laser beam incident regions (regions in the beam spot) incident on the pulse incident positions closest to each other increases as the pulse incident interval decreases. Therefore, in particular, the density of the total energy incident in the vicinity of the start point P _s is incident in the vicinity of the pulse incident position (for example, the pulse incident position P ₆ ) arranged on the locus through which the actual incident position passes during the equiangular velocity period. Higher than the total energy density. Thus, the energy density distribution in the circumferential direction of the trajectory T cannot be made uniform.

  In order to make the opening shape of the trepanning hole close to the circumference, the number of pulse incident positions arranged on the trajectory T (strictly on the trajectory of the actual incident position) should be sufficiently increased (described above). In the example, for the sake of explanation, the number of pulse incident positions is less than the actual machining). In order to increase the number of pulse incident positions, for example, when the pulse period is constant, the moving angular velocity of the target incident position may be decreased. Further, for example, when the moving angular velocity of the target incident position is constant, the pulse cycle may be shortened. The circumference indicated by the alternate long and short dash line in FIG. 4 shows the opening shape of the trepanning hole when the number of pulse incident positions is sufficiently large.

  For example, the repetition frequency of the pulse laser beam is 10 kHz. In this case, one trepanning hole is formed with 50 shots, for example. The time required for 50 shots of the pulse laser beam is 5 ms. The control cycle of the galvano control device is, for example, 50 μs. In this case, the number of target incident positions set on the trajectory T in order to open the trepanning hole (the number of target incident positions necessary for a period of 5 ms for opening the trepanning hole) is about 100.

  In the above-described example, the laser beam incident on the processing surface is terminated after the end point of the pulse incident position reaches the start point of the pulse incident position. In this case, the path from the start point to the end point of the target incident position is closed.

  However, even if the end point of the pulse incident position is located slightly before the start point of the pulse incident position, it is possible to make a trepanning hole. That is, even if the end point of the target incident position on the trajectory T is arranged slightly before the start point of the target incident position (a little before the end point of the target incident position on the trajectory T reaches the start point of the target incident position, It is possible to drill a trepanning hole (even if the movement of the target incident position is terminated). In this case, the path from the start point to the end point of the target incident position is not closed.

  A closed trajectory T can be defined to correspond to the desired trepanning hole to be formed on the work surface. Forming a trepanning hole by starting a target incident position on the trajectory T and causing the pulsed laser beam to enter the work surface while moving the target incident position along at least a part of the trajectory T. Can do.

  Next, the laser processing method according to the embodiment will be described with reference to FIG. In this method, the laser processing step (referred to as a trepanning scanning step) described with reference to FIG. 4 is repeated a plurality of times with different starting points in the circumferential direction of the trajectory T. Hereinafter, the case where the trepanning scanning process is repeated three times will be specifically described.

The upper part of FIG. 5 corresponds to the first step. A circumferential trajectory T is defined on the surface of the workpiece 6, and a point PS ₁ is disposed on the trajectory T. The first trepanning scanning process is performed starting from the point P _S1 . Thereby, the trepanning hole H is formed.

The middle part of FIG. 5 corresponds to the second process. On the trajectory T, the point P _S2 is arranged at a position shifted from the start point P _S1 of the first process by 120 ° clockwise. As a starting point the point P _S2, implementing the second trepanning scanning process. Thereby, the trepanning hole H is deepened.

The lower part of FIG. 5 corresponds to the third step. On the trajectory T, the starting point P _S2 of the second process is shifted 120 ° clockwise (or on the trajectory T, the starting point P _S1 of the first process is shifted 240 ° clockwise). , Point _PS3 is arranged. As a starting point the point P _S3, carrying out the third trepanning scanning process. Thereby, the trepanning hole H becomes deeper.

  In the laser processing method described with reference to FIG. 5, the trepanning scanning process is performed a plurality of times with different starting points. Thereby, since the position of the starting point with high energy density is dispersed in the circumferential direction on the track T, the energy density distribution in the circumferential direction of the track T can be made closer to uniform. That is, the energy density distribution can be made to be uniform in the circumferential direction of the opening of the formed trepanning hole. Thereby, improvement of the processing quality of the trepanning hole is achieved. In each trepanning scanning step, the galvano scanner is set when the target incident position is moved to the start point.

  As the pulse laser beam incident on the object to be processed, those having various wavelengths and various pulse periods can be used as necessary. For example, a pulsed laser beam having a wavelength in the ultraviolet region is used. Although what kind of thing may be processed, it is the resin member by which the copper foil was laminated | stacked on the surface, for example.

  Consider a case where an ultraviolet pulse laser beam is incident on such a resin member, a trepanning hole is formed through the copper foil and exposing the resin member on the bottom surface. When only one trepanning scan is performed, distortion from the circumferential shape of the opening shape of the hole is large in the vicinity of the scanning start point where the energy density is high. By performing trepanning scanning multiple times with different starting points as described above, the energy density distribution can be made uniform in the circumferential direction of the opening of the hole, so that compared to the case where only one trepanning scanning is performed, The opening shape approaches the circumferential shape (the roundness increases).

  In the above example, the trepanning scanning process is repeated three times. The start point of the second step is arranged at a position shifted from the start point of the first step by 120 ° in the circumferential direction of the trajectory T, and the start point of the third step is the circumference of the trajectory T. It was arranged at a position shifted by 120 ° in the direction. As a result, three start points corresponding to three steps are arranged at equal intervals in the circumferential direction of the track T. For example, as described above, the trepanning scanning process can be repeated a plurality of times with a process of repeating the trepanning scanning process three times.

  When N is an integer of 2 or more and the trepanning scanning process is repeated N times, the starting point of a certain trepanning scanning process is 360 ° / N in the circumferential direction of the trajectory T. By arranging them at positions shifted by (or an integral multiple thereof), it becomes easy to make the energy density distribution in the circumferential direction of the trajectory T uniform.

  Note that, from the viewpoint of making the energy density distribution in the circumferential direction of the trajectory T uniform, the amount of movement of the target incident position along the trajectory T in each trepanning scanning step is preferably equal. For example, for each time of the trepanning scanning process, M is set to an integer of 1 or more, and the target incident position is made to make M rounds on the trajectory T.

  Next, a laser processing method according to the first modification will be described with reference to FIG. In the method described with reference to FIG. 5, three trepanning scanning steps are continuously performed for one trepanning hole. This corresponds to burst processing. It is also possible to perform processing corresponding to cycle processing as follows.

As shown in FIG. 6A, a plurality of circumferential trajectories T _{1 to} T ₃ on which the laser beam is to be incident are defined on the surface of the workpiece 6. For each of the trajectories T _{1 to} T ₃ , as described with reference to FIG. 5, trepanning holes H _{1 to} H ₃ are formed by performing a trepanning scanning process, for example, three times with different starting points. To do. However, the trepanning scanning process is not performed twice for one trepanning hole. For example, performs first trepanning scanning step in order with respect to the track _T 1 through T _3, then a second time trepanning scanning step in order with respect to the track _T 1 through T _3, then the track _T 1 ~ A _third trepanning scanning process may be performed sequentially for T3.

Next, a laser processing method according to a second modification will be described with reference to FIG. Concentric circumferential tracks T _{4 to} T ₆ are defined on the surface of the workpiece 6. Track T ₅ is disposed outside the track T _4, trajectory T ₆ on the outside of the track T ₅ is arranged.

The radius of the trajectory T _5, the laser beam beam spot incident on the incident position on the trajectory T ₅ is larger to the extent that does not include the center of the track T _5. Thus, along the track T _5, while around the command incidence position and is incident pulsed laser beam on the work surface, rather than the hole, an annular groove along the track T ₅ is formed. The same applies to the track _{T 6.} Note that the case where the beam spot does not include the center of the trajectory and an annular groove is formed along the trajectory is referred to as a trepanning scanning process. The track T _4, the beam spot comprises a central track T _4, holes are formed by trepanning scanning process.

First, by trepanning scanning process for the track T _4, forming a hole corresponding to the track T _4. Then, by trepanning scanning process for the track T _5, to form an annular groove along the track T _5. An annular groove formed in the trepanning scanning process for the trajectory T ₅ is, so that it has an overlap with the hole formed by trepanning scanning process for track T _4, the radius of the track T ₅ is selected. Thus, it is possible to enlarge the radius of the hole formed by trepanning scanning process for the track T _4.

Furthermore, by trepanning scanning process for the track T _6, to form an annular groove along the track T _6. An annular groove formed in the trepanning scanning process for the track T ₆ is, so that it has an overlap with the annular groove formed by trepanning scanning process for track T _5, the radius of the track T ₆ is selected. Thereby, the radius of a hole can be expanded further. When the trepanning scanning process along the trajectories T _{4 to} T ₆ is completed, a hole H ₄ having a diameter equal to the outer diameter of the annular groove along the trajectory T ₆ is formed.

For each track T _4, T ₅ and T _6, if so at different starting performing a plurality of trepanning scanning step, the energy density distribution in the circumferential direction of the track T _4, T ₅ and T ₆ Can be close to uniform.

  Note that the trajectory for performing the trepanning scanning process is not limited to a circumferential shape. Even for a closed track other than a circular track, the energy density distribution in the track circumferential direction can be obtained by performing a plurality of trepanning scanning steps with different starting points in the track circumferential direction. Can be close to uniform.

  In addition, although the process which forms a hole with a laser beam was demonstrated, in the process which makes a laser beam inject into a process target similarly to the trepanning process of an Example even if it is not the process which forms a hole, a laser beam should be incident It is possible to make the energy density distribution in the circumferential direction of the track closer to uniform.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

It is the schematic of the laser processing apparatus by the Example of this invention. FIG. 3 is a block diagram of a main controller and a galvano controller for controlling a galvano scanner in the laser processing apparatus according to the embodiment. It is a graph which shows the time change of the rocking | fluctuation angle of a scanning mirror for demonstrating the setting of a galvano scanner. It is a top view of the process target object for demonstrating the laser processing method by the previous proposal of this inventor. It is a top view of the processed object for demonstrating the laser processing method by an Example. FIGS. 6A and 6B are plan views of the object to be processed for describing the laser processing methods according to the first and second modifications, respectively. It is a top view of the processing target object for demonstrating the conventional trepanning processing method. FIG. 6 is a block diagram of a main controller and a galvano controller for controlling a galvano scanner in a conventional laser processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 2 Galvano scanner 3 1st scanner 3a (1st scanner) Scanning mirror 3b (Swinging the scanning mirror of 1st scanner) Oscillation mechanism 4 2nd scanner 4a (2nd scanner ) Scanning mirror 4b (swinging the scanning mirror of the second scanner) Oscillating mechanism 5 fθ lens 6 Work object 7 Holding base 8 Main controller 9 Galvano controller T Trajectory P _s1 , P _s2 , P _{s3 Start} point H Trepanning hole

Claims (9)

In a method of performing laser processing using a beam scanner that scans a laser beam so that the incident position of the laser beam moves toward the target incident position after movement when the target incident position is moved on the workpiece,
(A) moving a target incident position of the beam scanner to a starting point on the trajectory of a workpiece on which a closed trajectory on which a laser beam is to be incident is defined on the surface;
While (b) the target incident position controls the beam scanner to move starting the start point along the trajectory, is incident pulsed laser beam onto the workpiece through the beam scanner, the pulse a beam spot between successive pulses to one another of the laser beam by overlapping partially, and a step wherein you irradiating the pulsed laser beam over the entire circumference of the track, by varying the starting point in the step (a) Laser processing method repeated at least twice.   The laser processing method according to claim 1, wherein in the step (b), the target incident position is moved along the trajectory without setting a beam scanner at each target incident position.   The laser processing method according to claim 1, wherein the step (a) includes a step of setting a beam scanner at a starting point on the orbit. Wherein In the step (b), the laser processing method according to any one of claims 1 to 3 pulses of the pulsed laser beam is incident on the workpiece at a constant period. Wherein In the step (b), the laser processing method according to any one of claims 1 to 4 with the movement of the target incident position for incident pulsed laser beam asynchronously. The trajectory is circular, N is an integer of 2 or more, and the steps (a) and (b) are repeated N times. The starting point of a certain step (a) and (b) is laser processing method in step (a) and starting point according to any one of claims 1 to 5 arranged in 360 ° / N or an integral multiple thereof shifted by a position in the circumferential direction of the trajectory of (b) . The M as an integer of 1 or more, the step (b) per laser processing method according to any one of claims 1 to 6 for M dividing the target incident position on the track. A holding table for holding a workpiece in which a closed track on which a laser beam is to be incident is defined on a surface;
A laser light source for emitting a pulsed laser beam;
When a pulse laser beam emitted from the laser light source is incident on a workpiece to be held on the holding table and a target incident position is input from the outside, the incident position of the pulse laser beam is directed toward the target incident position. A beam scanner that scans the pulsed laser beam to move; and
A controller for controlling the laser light source and providing a target incident position to the beam scanner;
The control device
(A) the position of the starting point on the trajectory of the workpiece, steps applied to the beam scanner as a target incident position, and (b) the target incident position is moved along said trajectory starting from the start point As described above, while changing the target incident position applied to the beam scanner, a pulse laser beam is emitted from the laser light source , and beam spots of successive pulses of the pulse laser beam are partially overlapped with each other. the laser processing apparatus of the pulsed laser beam process you irradiating over the entire circumference of the track is repeated at least twice with different starting point in the step (a).   In the step (b), the control device controls the beam scanner so as to move the target incident position along the trajectory without setting the beam scanner to each target incident position. The laser processing apparatus according to 8.

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