JP2018171632A - Laser processing device and laser processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing device and a laser processing method which can reduce determination, a labor and a time to obtain a target processing shape when processing a workpiece with a laser beam guided from a liquid jet.SOLUTION: A laser processing device includes: a processing head 40 which irradiates a workpiece W with a laser beam L while guiding the laser beam L with a liquid jet J; processed shape measuring means 72 which measures a processed shape formed by the processing head 40; and a control section 30 (laser beam distribution adjusting means) which adjusts laser beam distribution in a liquid jet J on a laser beam irradiation surface of the workpiece W based on comparison of the processed shape measured by the processed shape measuring means 72 with a target processed shape.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser processing apparatus and a laser processing method, and more particularly to a technique for processing a workpiece by laser light guided by a liquid jet.

  In recent years, with the high integration and miniaturization of devices such as IC and LSI, an inorganic film such as SiOF or BSG (SiOB) or a polymer film such as polyimide or parylene is used on the surface of a semiconductor substrate such as silicon. A wafer on which a device layer made of a laminated body in which a low dielectric constant insulating film (Low-k film) made of a certain organic film and a functional film forming a circuit are laminated has been put into practical use.

  However, dicing of a wafer having such a device layer is likely to cause film peeling and burrs, which is a serious problem in the dicing process. In particular, when a low-k film is included in the device layer, the low-k film is very fragile. Therefore, when the device layer is cut by a dicing blade, there is a problem that the low-k film is likely to be peeled off. That is, if the low-k film is broken by cutting with a dicing blade, and the broken area spreads over the device forming area (chip forming area), the chip becomes defective, and the yield of the semiconductor device to be manufactured is lowered. It will be a factor.

  In order to solve the above problem, prior to cutting with a dicing blade, a technique is disclosed in which a laser processing groove is formed along a dividing line called a street to divide a device layer and then cut with a dicing blade. (For example, refer to Patent Document 1).

  However, the technique disclosed in Patent Document 1 requires a laser processing apparatus (laser scriber) in addition to the dicing apparatus. Further, in the laser irradiation process, in order to form a laser processing groove wider than the width of the dicing blade, the laser beam irradiation must be performed by reciprocating along one street. For this reason, there is a problem that productivity is poor and the cost is increased.

  On the other hand, Patent Document 2 discloses a laser processing apparatus that injects pressurized liquid with a liquid jet and irradiates a workpiece with laser light using the liquid jet as an optical waveguide. In this laser processing device, a liquid jet is ejected toward the work piece, so that the laser beam is guided toward the work piece without being diffused by the liquid jet while preventing the effects of thermal damage and contamination during processing. Therefore, it becomes possible to perform highly accurate processing. Further, a dicing process such as dicing with a dicing blade or laser dicing is not required.

JP 2006-140311 A JP, 2006-193453, A

  By the way, when a workpiece is machined by laser light induced by a liquid jet, there is a problem that the machining shape changes even if the machining conditions (for example, the length of the liquid jet) are slightly different.

  In response to such a problem, the laser processing apparatus disclosed in Patent Document 2 includes a laser light distribution observation apparatus that observes the distribution of laser light induced by a liquid jet. In this laser light distribution observation device, the shielding plate and the photodetector are arranged in a conjugate relationship with each other with respect to the imaging lens, so that the laser beam distribution on the contact surface between the liquid jet and the shielding plate is detected. Can be faithfully reproduced on the light receiving surface of the instrument. Thereby, it is possible to observe the distribution of the laser light induced by the liquid jet.

  However, in the laser processing apparatus disclosed in Patent Document 2, in order to obtain an arbitrary processing shape (target processing shape), it is necessary to manually adjust the laser light distribution in the liquid jet and evaluate the processing shape several times manually. However, there is a problem that it takes time, judgment, and time to obtain a target machining shape.

  The present invention has been made in view of such circumstances, and when processing a workpiece with a laser beam guided by a liquid jet, it is possible to reduce judgment, labor, and time until a target processing shape is obtained. An object is to provide a laser processing apparatus and a laser processing method.

  In order to achieve the above object, a laser processing apparatus according to a first aspect of the present invention includes a laser oscillator, a processing head that irradiates a workpiece while guiding laser light output from the laser oscillator with a liquid jet, A moving means for relatively moving the machining head and the workpiece, a machining shape measuring means for measuring a machining shape formed by the machining head, a machining shape measured by the machining shape measuring means and a target machining of the workpiece Laser light distribution adjusting means for adjusting the laser light distribution in the liquid jet on the laser light irradiation surface of the workpiece based on the comparison with the shape.

  In the laser processing apparatus according to the second aspect of the present invention, in the first aspect, the laser light distribution adjusting unit compares the processing shape measured by the processing shape measuring unit with the target processing shape of the workpiece, and calculates an error. If the error is outside the allowable error range, the laser light distribution is adjusted based on the error.

  A laser processing apparatus according to a third aspect of the present invention includes, in the first aspect or the second aspect, a high-speed deflecting unit that deflects laser light at high speed on the way from the laser oscillator to the processing head, and the laser light distribution adjusting unit includes: Based on the comparison between the machining shape measured by the machining shape measuring means and the target machining shape of the workpiece, the laser light distribution is adjusted by changing the deflection condition of the high-speed deflection means.

  A laser processing apparatus according to a fourth aspect of the present invention includes, in the third aspect, a low-speed deflection unit that deflects the laser beam output from the laser oscillator toward the machining head, and the high-speed deflection unit is more than the low-speed deflection unit. High speed deflection and narrow range deflection.

  In the laser processing apparatus according to the fifth aspect of the present invention, in the third aspect or the fourth aspect, the high-speed deflection means is an acousto-optic deflection element.

  According to a sixth aspect of the present invention, there is provided a laser processing apparatus according to any one of the third to fifth aspects, wherein the laser light distribution observation means for observing the laser light distribution and the laser observed by the laser light distribution observation means. An expected machining shape calculating means for calculating an expected machining shape when the workpiece is machined by the machining head based on the light distribution, and the laser light distribution adjusting means is calculated by the expected machining shape calculating means. The laser light distribution is adjusted based on a comparison between the predicted machining shape and the target machining shape of the workpiece.

  The laser processing apparatus according to a seventh aspect of the present invention is the laser processing apparatus according to the sixth aspect, wherein the laser light distribution adjusting means compares the predicted processing shape calculated by the predicted processing shape calculation means with the target processing shape of the workpiece and produces an error. If the error is outside the allowable error range, the laser light distribution is adjusted based on the error.

  A laser processing apparatus according to an eighth aspect of the present invention is the laser processing apparatus according to the sixth aspect or the seventh aspect, wherein the workpiece is irradiated with laser light from the processing head while the processing head and the workpiece are relatively moved by the moving means. The high-speed deflection control means for switching the laser light distribution to a plurality of distributions by changing the deflection conditions of the high-speed deflection means, and the predicted machining shape calculation means is configured to detect the laser light observed by the laser light distribution observation means. Based on the plurality of distributions, an expected machining shape is calculated when the workpiece is machined by the machining head while the laser beam distribution is switched to the plurality of distributions by the high-speed deflection control means.

  In the laser processing apparatus according to the ninth aspect of the present invention, in the eighth aspect, the high-speed deflection control means is configured such that the peak position of the laser light in the laser light distribution is orthogonal to the relative movement direction of the processing head and the workpiece. The deflection condition of the high-speed deflection means is changed so that the scanning is performed in the direction.

  A laser processing method according to a tenth aspect of the present invention includes a laser light irradiation step of irradiating a workpiece with laser light guided by a liquid jet, and a movement step of relatively moving the liquid jet and the workpiece. Based on the machining shape measurement step for measuring the machining shape formed by the laser beam and the comparison between the machining shape measured in the machining shape measurement step and the target machining shape of the workpiece, the laser beam irradiation surface of the workpiece A laser light distribution adjusting step for adjusting the laser light distribution in the liquid jet.

  According to the present invention, when processing a workpiece with laser light guided by a liquid jet, the laser light distribution in the liquid jet is automatically adjusted based on a comparison between the actual processing shape and the target processing shape. Therefore, it is possible to reduce the judgment, labor, and time until the target machining shape is obtained. As a result, it is possible to reduce the number of work steps and improve the production efficiency by shortening the time required for laser processing, and to obtain the target processing shape with high accuracy.

Schematic which shows the structure of the laser processing apparatus which concerns on 1st Embodiment. Simplified diagram showing the laser beam path in a liquid jet. The figure which showed the result of having observed the distribution of the laser beam in the position shown to a of FIG. The figure which showed the result of having observed the distribution of the laser beam in the position shown to b of FIG. The figure which showed the depth profile of the processing groove when the linear processing groove was formed in the work on the same conditions as FIG. The figure which showed the depth profile of the processing groove when the linear processing groove was formed in the work on the same conditions as FIG. Explanatory drawing schematically showing the case of laser processing with the laser light distribution in the liquid jet constant Explanatory drawing schematically showing the case of laser processing while switching the laser light distribution in the liquid jet to multiple distributions Explanatory drawing schematically showing the case of laser processing while switching the laser light distribution in the liquid jet to multiple distributions Explanatory drawing schematically showing the case of laser processing while switching the laser light distribution in the liquid jet to multiple distributions The figure for demonstrating the processing result when performing laser processing, switching the laser beam distribution in a liquid jet into two distributions by a high-speed deflection means The figure for demonstrating the processing result when performing laser processing, switching the laser beam distribution in a liquid jet into two distributions by a high-speed deflection means The figure for demonstrating the processing result when performing laser processing, switching the laser beam distribution in a liquid jet into two distributions by a high-speed deflection means A flowchart which shows an example of the laser processing method using the laser processing apparatus concerning a 1st embodiment. Figure showing an example of a reference table The figure which showed the 1st example of the calculation method of an expected processing shape The figure which showed the 1st example of the calculation method of an expected processing shape The figure which showed the 2nd example of the calculation method of a predicted processing shape The figure which showed the 2nd example of the calculation method of a predicted processing shape The figure which showed the 2nd example of the calculation method of a predicted processing shape The figure which showed the 3rd example of the calculation method of a predicted machining shape The figure which showed the 3rd example of the calculation method of a predicted machining shape The figure which showed the 3rd example of the calculation method of a predicted machining shape Log-log graph showing an example of correspondence between irradiation fluence and processing rate Conceptual diagram for explaining a laser processing method in a case where laser processing is performed with a laser beam distribution in a liquid jet constant in one processing pass. Schematic which shows the structure of the laser processing apparatus which concerns on 2nd Embodiment. The figure for demonstrating the effect of the phase adjustment by a spatial light phase modulator Schematic which shows the structure of the laser processing apparatus which concerns on 3rd Embodiment. The figure for demonstrating the effect of 3rd Embodiment The figure for demonstrating the effect of 3rd Embodiment

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a schematic diagram showing a configuration of a laser processing apparatus 10 according to the first embodiment.

  As shown in FIG. 1, the laser processing apparatus 10 includes a laser power source 12, a laser oscillator 14, a work table 16, a work table moving unit 18, a liquid supply means 20, a head unit 22, and laser light distribution observation. A device 26 and a control unit 30 are provided.

  The laser power source 12 is connected to the laser oscillator 14 via a signal cable and supplies power to the laser oscillator 14.

  The laser oscillator 14 outputs the laser light L using the power supplied from the laser power source 12. As the laser beam L, a laser beam having a wavelength region that is difficult to be absorbed by water is used.

  The work table 16 has a holding surface 16a that sucks and holds the work W (workpiece). The holding surface 16a is provided with a plurality of suction holes for sucking and holding the workpiece W, and the suction holes are connected to a vacuum suction source (not shown).

  The work table moving unit 18 includes an X table 32 and a θ rotation table 34. The X table 32 is installed horizontally and is configured to be movable in the X direction by an X drive mechanism (not shown). The θ rotation table 34 is disposed on the X table 32 and is configured to be movable in the θ direction (rotation direction about the Z direction axis) by a θ drive mechanism (not shown). The work table 16 is placed and fixed on the θ rotation table 34. Therefore, the work table 16 is configured to be movable in the X direction and the θ direction, respectively. The work table moving unit 18 is an example of a moving unit.

  The liquid supply unit 20 is connected to the processing head 40 of the head unit 22 via a liquid supply path, and supplies pressurized liquid (for example, pressurized water) to the processing head 40.

  The head unit 22 includes a deflection unit 36, a beam shape shaping unit 38, and a processing head 40. The head unit 22 is disposed on a Z table configured to be movable in the Z direction by a Z drive mechanism (not shown). The Z table is arranged in a Y table configured to be movable in the Y direction by a Y drive mechanism (not shown). Therefore, the head unit 22 is configured to be movable in the Y direction and the Z direction.

  The deflecting unit 36 is provided on the optical path of the laser beam L, and reflects the laser beam L output from the laser oscillator 14 toward the machining head 40. The deflecting unit 36 is configured to face two galvanometer mirrors (not shown) that can swing around mutually orthogonal axes, and deflects the laser light L by swinging the two galvanometer mirrors. Thus, the incident angle and the incident position with respect to the liquid jet J ejected from the processing head 40 (liquid jet ejection nozzle 48) can be changed. The deflection unit 36 is an example of a low-speed deflection unit.

  The beam shape shaping means 38 is disposed between the deflection unit 36 and the machining head 40 and shapes the laser beam L input from the laser oscillator 14 via the deflection unit 36. The beam shape shaping means 38 includes, for example, a variable aperture (rectangular or circular), an axicon lens, a beam homogenizer, and a mechanism for minutely moving these in a direction perpendicular to the laser beam L. Is shaped into a predetermined shape, size, and intensity distribution. In addition, the laser light L can be statically or dynamically included, including the branching of the laser light L, using an AOD (acousto-optic deflection element), SLM (spatial modulation element), DMD (Digital Mirror Device), diffraction element, calcite, and the like. Can also be shaped.

  The processing head 40 ejects the pressurized liquid supplied from the liquid supply means 20 toward the workpiece W by the liquid jet J, and guides the laser light L into the liquid jet J, whereby the liquid jet J The workpiece W is irradiated with the laser beam L guided by the above. A specific configuration of the machining head 40 is as follows.

  The processing head 40 includes a condenser lens 42 and a head main body 44.

  The condensing lens 42 is disposed in front (upper) of the head main body 44, and condenses the laser light L incident from the laser oscillator 14 via the deflection unit 36 and the beam shape shaping unit 38 toward the inside of the head main body 44. To do.

  A liquid chamber 46 is defined in the head main body 44. The liquid chamber 46 stores the high-pressure liquid supplied from the liquid supply means 20. In addition, a liquid jet spray nozzle 48 is provided below the head main body 44, and the liquid jet spray nozzle 48 communicates with the liquid chamber 46. Therefore, when the high-pressure liquid is supplied from the liquid supply means 20 to the processing head 40, the pressurized liquid is accommodated in the liquid chamber 46, and the workpiece W (or laser light distribution observation described later) is further supplied from the liquid jet injection nozzle 48. The liquid jet J is ejected towards the shielding plate 52) of the device 26.

  A window portion 50 is provided on the upper portion of the head main body 44. The window 50 is made of a light-transmissive member (for example, quartz glass) that is optically transparent to the laser light L, seals the liquid chamber 46 and transmits the laser light L. Accordingly, the laser light L emitted from the condensing lens 42 passes through the window portion 50 and enters the inside of the head main body 44 (liquid chamber 46) and is condensed on the liquid jet ejection nozzle 48.

  In the present embodiment, as an example, the work table 16 is configured to be movable in the X direction and the θ direction, and the head unit 22 is configured to be movable in the Y direction and the Z direction. 16 and the head unit 22 may be configured to be relatively movable in the X direction, the Y direction, the Z direction, and the θ direction, and other modes different from the present embodiment can be appropriately employed. The same applies to other embodiments described later.

  The laser light distribution observation device 26 observes the distribution (laser light distribution) of the laser light L in the liquid jet J on the surface (laser light irradiation surface) of the workpiece W.

  The laser light distribution observation device 26 is disposed at a position facing the processing head 40 instead of the work table 16 when observing the laser light distribution in the liquid jet J.

  The laser light distribution observation device 26 includes an observation device driving mechanism (not shown) and is configured to be movable in the X direction, the Y direction, and the Z direction. Thereby, the laser beam distribution observation device 26 can move between an observation position facing the processing head 40 and a retracted position separated from the observation position.

  The laser light distribution observation device 26 includes a shielding plate 52, a liquid removing unit 54, an imaging lens 56, and a photodetector 58.

  The shielding plate 52 is provided on the upper surface of the laser light distribution observation device 26 (the surface facing the processing head 40). The shielding plate 52 is composed of a light transmission member (for example, quartz glass) that is optically transparent to the laser light L, shields the liquid jet J, and transmits the laser light L. Therefore, while the liquid of the liquid jet J ejected from the liquid jet ejection nozzle 48 of the processing head 40 is shielded by the shielding plate 52, the laser light L guided to the liquid jet J passes through the shielding plate 52, and the laser The light enters the main body 60 constituting the light distribution observation device 26.

  The shielding plate 52 is disposed at the same height as the work W held on the work table 16 with respect to the processing head 40. The distance between the machining head 40 and the shielding plate 52 may be equal to the distance between the machining head 40 and the workpiece W. That is, the length of the liquid jet J when the liquid jet J is ejected from the machining head 40 onto the workpiece W and the length of the liquid jet J when the liquid jet J is ejected from the machining head 40 onto the shielding plate 52 are mutually equal. The workpiece W and the shielding plate 52 are not necessarily required to have the same height in absolute coordinates. For example, even if the workpiece W and the shielding plate 52 have different heights in absolute coordinates, the relative heights with respect to the processing head 40 may be the same. The distance between the processing head 40 and the shielding plate 52 becomes equal to the distance between the processing head 40 and the workpiece W due to movement of the head unit 22 (processing head 40) or the laser light distribution observation device 26 in the Z direction. To be adjusted.

  The liquid removing unit 54 removes the liquid (residual liquid) of the liquid jet J shielded by the shielding plate 52. As the liquid removing means 54, for example, a liquid absorbing means for removing residual liquid by absorption, a liquid suction means for removing residual liquid by suction, a liquid blowing means for removing residual liquid by blowing, or a combination of these is appropriately used. Can be adopted. In addition, as a liquid absorption means, it is preferable to employ | adopt the structure which makes a strip | belt member absorb a residual liquid using a capillary phenomenon by making a fibrous strip | belt-shaped member, such as cloth, contact | abut to the surface of the shielding board 52. FIG. it can.

  The imaging lens 56 is disposed between the shielding plate 52 and the photodetector 58 inside the main body 60. The imaging lens 56 is composed of a plurality of lenses, and projects the laser light distribution in the liquid jet J onto the light receiving surface of the photodetector 58. That is, the shielding plate 52 and the light detector 58 are arranged in a conjugate relationship with each other with respect to the imaging lens 56, and the laser light distribution in the liquid jet J at the contact surface between the liquid jet J and the shielding plate 52. Is faithfully reproduced on the light receiving surface of the photodetector 58 by the imaging lens 56.

  The light detector 58 receives a projection image indicating the laser light distribution in the liquid jet J imaged by the imaging lens 56. The photodetector 58 has a plurality of light receiving elements arranged two-dimensionally, and each light receiving element outputs an output signal (electric signal) corresponding to the amount of received light as laser light distribution data. As the photodetector 58, for example, a solid-state imaging device such as a CCD image sensor (Charge Coupled Device Image Sensor) or a CMOS image sensor (Complementary Metal Oxide Semiconductor Image Sensor) is preferably used.

  Here, the operation when the laser light distribution observation device 26 observes the laser light distribution in the liquid jet J will be described.

  First, the laser light distribution observation device 26 is moved to an observation position (a position facing the processing head 40) by an observation device driving mechanism (not shown). The shielding plate 52 is disposed at the same height relative to the work W held on the work table 16 with respect to the processing head 40.

  Next, the pressurized liquid is supplied from the liquid supply means 20 to the processing head 40. The pressurized liquid supplied to the processing head 40 is accommodated in the liquid chamber 46, and the liquid jet J is ejected from the liquid jet ejection nozzle 48 toward the shielding plate 52.

  The laser light L output from the laser oscillator 14 is deflected toward the processing head 40 by the deflecting unit 36 via a high-speed deflecting unit 68 described later, and has a predetermined shape, size, and intensity by the beam shape shaping unit 38. The light is shaped into a distribution and enters the condenser lens 42. Further, the laser light L is condensed by the condenser lens 42 onto the liquid jet spray nozzle 48 through the window 50. Accordingly, the laser light L is guided to the liquid jet J, guided by the liquid jet J, and irradiated toward the shielding plate 52.

  On the other hand, the liquid jet J ejected from the liquid jet ejection nozzle 48 is shielded by the shielding plate 52, and the laser light L guided by the liquid jet J passes through the shielding plate 52 and is emitted by the imaging lens 56. An image is formed on the light receiving surface of the detector 58. At this time, since the shielding plate 52 and the photodetector 58 are disposed in an optically conjugate positional relationship with respect to the imaging lens 56, the inside of the liquid jet J at the contact surface between the liquid jet J and the shielding plate 52 is provided. Is reproduced faithfully on the light receiving surface of the photodetector 58 by the imaging lens 56.

  When a projection image showing the laser light distribution in the liquid jet J is formed on the light receiving surface of the light detector 58 in this way, each light receiving element of the light detector 58 outputs an output signal corresponding to the amount of received light to the laser. It outputs to the control part 30 as light distribution data. The control unit 30 performs various processes on the input laser light distribution data, and displays an image based on the laser light distribution data subjected to the process on the monitor 64.

  As described above, according to the laser light distribution observation apparatus 26 of the present embodiment, the laser light distribution in the liquid jet J on the contact surface between the liquid jet J and the shielding plate 52 (that is, the surface of the workpiece W) can be observed. It becomes possible.

  Further, when the laser light distribution observation device 26 observes the laser light distribution in the liquid jet J, the liquid (residual liquid) of the liquid jet J shielded by the shielding plate 52 is removed by the liquid removing means 54. Therefore, it is possible to stably and accurately observe the laser light distribution in the liquid jet J without being affected by the scattering of the laser light L by the residual liquid on the shielding plate 52.

  In addition to the above-described configuration, the laser processing apparatus 10 according to the present embodiment further includes a high-speed deflection unit 68 and a processing shape measuring unit 72.

  The high-speed deflecting unit 68 deflects the laser light L at high speed on the way from the laser oscillator 14 toward the processing head 40 (that is, before entering the liquid jet J). That is, the high-speed deflecting unit 68 deflects the laser light L output from the laser oscillator 14 within a predetermined angle range, and switches the deflection angle and emission direction of the laser light L at high speed. As the high-speed deflection means 68, for example, an AOD (acousto-optic deflection element) is preferably used. AOD deflects the laser beam L at high speed by changing the frequency of an applied high frequency signal (RF signal). Note that the deflection conditions (deflection angle, deflection direction, and deflection timing) of the high-speed deflection unit 68 are controlled by the control unit 30 (an example of the high-speed deflection control unit).

  It is desirable that the switching speed (frequency) of the high-speed deflection means 68 can be obtained up to about several MHz. Further, the high-speed deflecting means 68 may be used in combination with means for branching the laser light L such as a diffractive optical element.

  The machining shape measuring means 72 is disposed at a position adjacent to the machining head 40. The machining shape measuring means 72 is a means for three-dimensionally measuring the machining shape formed on the surface of the workpiece W by the machining head 40. The machining shape measuring means 72 is preferably a non-contact type that performs measurement without contacting the surface of the workpiece W. For example, a laser microscope or a white interference microscope can be preferably employed. The three-dimensional data (machining shape data) of the machining shape measured by the machining shape measuring means 72 is output to the control unit 30.

  The control unit 30 includes a CPU, a memory, an input / output circuit unit, various control circuit units, and the like, and controls the operation of each unit of the laser processing apparatus 10. That is, the control unit 30 controls operations of the laser oscillator 14, the work table moving unit 18, the liquid supply unit 20, the head unit 22, the high-speed deflection unit 68, and the machining shape measurement unit 72.

  Although details will be described later, the control unit 30 functions as a high-speed deflection control unit that controls the deflection conditions of the high-speed deflection unit 68. The control unit 30 functions as an expected machining shape calculation unit that calculates an expected machining shape when the workpiece W is machined by the machining head 40 based on the laser beam distribution observed by the laser beam distribution observation device 26. Further, the control unit 30 adjusts the laser light distribution in the liquid jet J on the surface of the workpiece W based on the comparison between the machining shape of the workpiece W measured by the machining shape measuring unit 72 and the target machining shape of the workpiece W. It functions as a laser light distribution adjusting means.

  Here, an operation principle of laser processing performed by the laser processing apparatus 10 of the present embodiment will be described. In the following, first, the laser light distribution in the liquid jet J will be described, and then the effects obtained when laser processing is performed while switching the laser light distribution in the liquid jet J to a plurality of distributions by the high-speed deflection means 68 will be described. To do.

  FIG. 2 is a simplified diagram showing a laser beam path in the liquid jet J when the laser beam L is incident on the same axis as the central axis of the liquid jet J. FIG. Since the liquid jet J has a function similar to that of the SI type multi-mode optical fiber, the moving speed in the central axis direction (longitudinal direction) of the liquid jet J actually changes for each angle of entry into the liquid jet J. It is thought that they are complicated by speckle noise generated by microscopic irregularities on the cylindrical outer peripheral surface (cylindrical surface) of the liquid jet J, but they are simplified for the sake of simplicity. Will be described.

  As shown in FIG. 2, when the laser light L collected by the condenser lens 42 is incident on the same axis as the central axis of the liquid jet J, the laser light L is repeatedly expanded and contracted by total reflection in the liquid jet J. Guided along the central axis direction. For example, the position shown by a in FIG. 2 corresponds to the antinode portion of the laser beam path (the portion where the laser beam L is enlarged), so that the sectional shape of the laser beam L at that position (the sectional shape perpendicular to the central axis of the liquid jet J) ) Uniformly spread over the entire liquid jet diameter. On the other hand, at the position indicated by b in FIG. 2, the laser light L gathers only in a narrow range at the center of the liquid jet J because it corresponds to a node portion (a portion where the laser light L is reduced) of the laser light path.

  FIG. 3 is a diagram showing a result of actually observing the distribution of the laser beam L at a position corresponding to the position shown in FIG. 2a, and FIG. 4 is a position corresponding to the position shown in FIG. 5 is a diagram showing the depth profile of the machining groove when a linear machining groove is formed on the workpiece W under the same conditions as FIG. 3, and FIG. 6 is the same condition as FIG.

  As can be seen from these figures, the laser light distribution in the liquid jet J varies depending on the position of the liquid jet J in the central axis direction, that is, the length of the liquid jet J. The machining shape changes according to the change.

  Therefore, by performing control to change the laser light distribution in the liquid jet J on the surface (laser light irradiation surface) of the workpiece W, a processed shape corresponding to the change in the laser light distribution in the liquid jet J can be obtained. .

  Next, the operation and effect when laser processing is performed while the laser beam distribution in the liquid jet J is switched to a plurality of distributions by the high-speed deflection means 68 will be described.

  FIG. 7 is an explanatory view schematically showing a case where laser processing is performed in a state where the laser light distribution in the liquid jet J is constant. 8 to 10 are explanatory views schematically showing a case where laser processing is performed while switching the laser light distribution in the liquid jet J to a plurality of distributions. Note that, on the left side of these drawings, the liquid jet J is moved relative to the workpiece W in the machining feed direction (direction along the scheduled cutting line) M to form a linear machining groove K in the workpiece W. The locus of the peak position Q of the laser beam L induced by the liquid jet J (the position where the light intensity of the laser beam L is highest on the surface of the workpiece W) is shown. Further, on the right side of these drawings, a depth profile of the machining groove K formed in the workpiece W is shown.

  In each figure, the intensity of the peak position Q of the laser beam L in the liquid jet J is assumed to be uniform for the sake of simplicity. In addition, although the peak positions Q of the laser beams L in the liquid jet J are depicted as being separated from each other, if it is desired to form a uniform processing groove in the processing feed direction M, it is spatially 90% or more. Laser processing is preferably performed under overlapping conditions.

  As shown in FIG. 7, when laser processing is performed with the laser light distribution in the liquid jet J being constant, the peak position Q of the laser light L in the liquid jet J is along the processing feed direction M. It becomes the state arranged in one line. For this reason, in the processing groove K, the processing depth at the position corresponding to the peak position Q of the laser beam L in the liquid jet J is deeper than the processing depth at other positions. In such a case, in order to make the processing depth of the processing groove K uniform in the entire width direction, it is necessary to perform processing a plurality of times in one processing pass, which causes a reduction in the overall throughput. It becomes.

  On the other hand, as shown in FIG. 8, when laser processing is performed while the laser distribution in the liquid jet J is switched to a plurality of distributions by the high-speed deflection means 68, the peak position of the laser light L in the liquid jet J Q can be changed in a direction perpendicular to the machining feed direction M (width direction of the machining groove).

  In the example shown in FIG. 8, when laser processing is performed while moving the liquid jet J relative to the workpiece W in the processing feed direction M, the peak position Q of the laser beam L in the liquid jet J is processed and sent. Laser processing is performed while sequentially changing at different intervals (pitch) P at different positions in a direction orthogonal to the direction M. In this case, the processing depth of the processing groove K can be made uniform over the entire width direction. Therefore, as compared with the example shown in FIG. 7, it is possible to obtain a desired processing shape without repeatedly performing processing in one processing pass, and it is possible to improve the overall throughput.

  In the example shown in FIG. 8, the peak position Q of the laser light L in the liquid jet J is from one side (upper side in FIG. 8) in the direction perpendicular to the machining feed direction M (the width direction of the machining groove K) to the other. The other end of the laser beam L in the direction perpendicular to the machining feed direction M (see FIG. 8) is sequentially changed at a constant interval P toward the side (lower side in FIG. 8). At the lower end of the liquid jet J, the peak position Q of the laser light L in the liquid jet J is switched to one end in the direction orthogonal to the machining feed direction M, and thereafter the liquid jet is processed in the same order. The peak position Q of the laser beam L in J changes sequentially.

  On the other hand, in the example shown in FIG. 9, the peak position Q of the laser light L in the liquid jet J is changed from one side (upper side in FIG. 9) to the other side (lower side in FIG. 9). When the peak position Q of the laser light L in the liquid jet J reaches the other end in the direction orthogonal to the machining feed direction M, the liquid jet The peak position Q of the laser beam L in J sequentially changes at a constant interval P from the other side in the direction orthogonal to the machining feed direction M to the one side, and thereafter the laser beam in the liquid jet J in the same order. The peak position Q of L changes sequentially. According to the example shown in FIG. 9, since the interval P between the peak positions Q of the laser beams L adjacent in the direction orthogonal to the machining feed direction M is always constant, the laser is compared with the example shown in FIG. Switching traces of the peak position Q of the light L are less likely to appear, and the processing quality in laser processing can be further improved.

  The example shown in FIG. 10 is a case where the number of times of the peak position Q of the laser beam L at both ends in the direction orthogonal to the machining feed direction M is distributed more than in the example shown in FIG. In this case, the processing depth at both end portions in the width direction of the processing groove K can be processed deeper than the central portion. Although illustration is omitted, when the number of times of the peak position Q of the laser beam L in the central portion in the direction orthogonal to the processing feed direction M is distributed a lot, the processing depth in the central portion in the width direction of the processing groove K Can be processed deeper than both ends.

  As described above, in the laser processing apparatus 10 of the present embodiment, laser processing is performed while switching the laser light distribution in the liquid jet J on the surface of the workpiece W to a plurality of distributions by deflecting the laser light L at high speed by the high speed deflecting means 68. It can be performed. Thereby, the laser beam distribution in the liquid jet J can be actively controlled, and an arbitrary machining shape (target machining shape) can be obtained without repeatedly performing machining in one machining pass.

  At this time, the control unit 30 functioning as a high-speed deflection control unit performs high-speed deflection unit so that the peak position Q of the laser light L in the laser distribution in the liquid jet J is scanned in a direction orthogonal to the processing feed direction. Control for changing 68 deflection conditions (deflection angle, deflection direction, and deflection timing) is performed.

  FIGS. 11 to 13 are diagrams for explaining processing results when laser processing is performed while the laser beam distribution in the liquid jet J is switched between two distributions by the high-speed deflecting means 68. Here, the result when the single mode laser beam L is used is shown.

  FIG. 11 is a diagram showing a result of observing two laser light distributions to be switched by the high-speed deflecting means 68 with the laser light distribution observation device 26. FIG. 12 shows projection data obtained by projecting the two laser light distributions shown in FIG. 11 in a direction perpendicular to the machining feed direction (left and right direction in FIG. 11). Note that (a) and (b) in each figure correspond to each other.

  FIG. 13 shows the processing obtained when the linear processing grooves are formed while alternately switching the two laser light distributions shown in FIGS. 11 and 12 at the same ratio (the use ratio of 1: 1 in this example). It shows the depth profile of the groove. Here, the laser processing was performed while the movement speed (processing feed speed) of the workpiece W in the processing feed direction (X direction) was transported at 30 mm / s while switching the two laser light distributions at 15 kHz by the high-speed deflection means 68. Shows the results when. This is equivalent to switching the laser light distribution in the liquid jet J every time the machining distance (the movement distance of the workpiece W in the machining feed direction) advances by 2 μm. As shown in FIG. The processing depth is a shape averaged over the entire width direction of the processing width.

  When the switching speed of the laser light distribution in the liquid jet J is slow, the peak position Q of the laser light L in the liquid jet J changes with the switching of the laser light distribution in the liquid jet J with respect to the processing feed direction. When switching, a switching mark appears, and an uneven shape is formed in the processed groove. For example, when two laser light distributions are switched alternately, when laser processing is performed under the condition that the processing feed speed is 50 mm / s and the switching speed of the two laser light distributions is 500 Hz, one laser light is used. Since the processing distance per distribution is 100 μm (that is, the laser light distribution is switched every time the processing distance increases by 100 μm), unevenness is formed every 100 μm in the processing feed direction (longitudinal direction of the processing groove).

  On the other hand, when laser processing is performed under the condition that the processing feed rate is 50 mm / s and the switching speed of the two laser light distributions is 50 kHz, the continuous processing distance is 1 μm, and the unevenness of the processing groove is Cannot be determined.

  Next, a laser processing method using the laser processing apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 14 is a flowchart illustrating an example of a laser processing method using the laser processing apparatus 10 according to the present embodiment. Note that each processing is executed under the control of the control unit 30 unless otherwise specified.

(Step S10: target machining shape setting step)
First, when one machining shape is selected from a plurality of machining shapes registered in advance in the laser machining apparatus 10, the control unit 30 sets the selected machining shape as a target machining shape. Instead of selection by the user, the laser processing apparatus 10 may automatically set a predetermined default shape as the target processing shape. As shown in FIG. 15, the laser processing apparatus 10 includes a plurality of processing shapes (K1 to K3), a plurality of laser light distributions (PT1 to PT9) corresponding to the processing shapes, and lasers. A reference table (look-up table) indicating a correspondence relationship between the usage ratio of the light distribution and the deflection patterns (C1 to C9) of the high-speed deflection means 68 corresponding to each laser light distribution is stored in a memory (not shown). ing. Further, a plurality of laser light distributions (for example, laser light distributions PT1 and PT2) corresponding to the same processed shape can be realized by changing the deflection pattern (deflection angle and deflection direction) of the high-speed deflection means 68. To do.

(Step S12: Laser light distribution setting step)
Next, the control unit 30 performs processing conditions (for example, a mirror of the deflection unit 36) of each part of the apparatus so that the laser light distribution corresponding to the target processing shape set in the target processing shape setting step (step S10) is realized. Angle). In addition, the laser processing apparatus 10 shall be previously memorize | stored in memory (not shown) as the internal value of the process conditions of each part of the apparatus corresponding to each process shape.

(Step S14: Laser light distribution acquisition step)
Next, the laser light distribution in the liquid jet J is observed by the laser light distribution observation device 26. At this time, if the laser light distribution observation device 26 is not at the observation position of the laser light distribution (position facing the processing head 40), the laser light distribution observation device 26 is moved to the observation position by an observation device driving mechanism (not shown). Further, when observing the laser light distribution, if the intensity of the laser light L irradiated from the processing head 40 toward the laser light distribution observation device 26 exceeds the observable range of the laser light distribution observation device 26, the beam The shape shaping means 38 is adjusted so as to reduce the intensity of the laser light L. Laser light distribution data indicating the laser light distribution in the liquid jet J observed by the laser light distribution observation device 26 is output to the control unit 30. Note that the observation of the laser light distribution in the liquid jet J by the laser light distribution observation device 26 is performed for each of the laser light distributions corresponding to the target processing shape.

(Step S16: Expected machining shape calculation step)
Next, the control unit 30 functions as an expected machining shape calculation unit, and predicts when the workpiece W is machined by the machining head 40 based on the laser light distribution observed in the laser light distribution acquisition step (step S14). The machining shape is calculated. Specifically, the laser light distribution data indicating each laser light distribution observed by the laser light distribution observation device 26 is converted into projection data projected in a direction orthogonal to the machining feed direction. Then, the projected processing shape is calculated by adding the data obtained by multiplying the projection data of each laser light distribution by the usage ratio of each laser light distribution (see FIG. 15). The predicted machining shape calculated by the control unit 30 is displayed on the monitor 64. Thereby, the user can grasp | ascertain easily the estimated process shape after a process.

  Here, a method of calculating the predicted machining shape will be described with reference to FIGS.

  16 and 17 are diagrams illustrating a first example of a predicted machining shape calculation method.

  The two laser light distributions 100A and 100B shown in FIGS. 16A and 16B are graphs showing projection data projected in a direction orthogonal to the machining feed direction, and the horizontal axis indicates the laser light L. The distribution horizontal width (direction orthogonal to the machining feed direction), and the vertical axis represents the distribution intensity (laser light intensity) of the laser light L.

  In the laser light distribution 100A shown in FIG. 16A, the peak position of the laser light L is biased to one side (left side of the figure) of the distribution width, whereas the laser light shown in FIG. In the distribution 100B, the peak position of the laser beam L is biased to the other side of the distribution width (the right side in the figure). Further, the peak intensities of the two laser light distributions 100A and 100B are the same.

  Using such laser light distributions 100A and 100B, the calculation result of the predicted machining shape 200A when laser machining is performed while switching the laser light distributions 100A and 100B at a use ratio of 1: 1 in one machining pass is shown. As shown in FIG. The predicted processed shape 200A shown in FIG. 17 adds data obtained by multiplying the two laser light distributions 100A and 100B shown in FIGS. 16A and 16B by a use ratio of 1: 1. Can be obtained.

  18 to 20 are diagrams illustrating a second example of the method of calculating the predicted machining shape.

  The two laser light distributions 100C and 100D shown in FIGS. 18A and 18B have the same bias shape as the two laser light distributions 100A and 100B shown in FIGS. However, the difference is that the peak intensity ratio is 1: 2.

  Using such laser light distributions 100C and 100D, the calculation result of the expected machining shape 200B when the laser machining is performed while switching the laser light distributions 100C and 100D at a use ratio of 1: 1 in one machining pass. It shows in FIG. In this case, since the peak intensities of the two laser light distributions 100C and 100D are different, when the usage ratio is 1: 1, as shown in FIG. 19, the predicted processing shape 200B has a bottom surface of the processing groove. It is not uniform in the width direction (left-right direction in the figure).

  FIG. 20 shows the calculation result of the predicted machining shape 200C when laser machining is performed while switching the laser light distributions 100C and 100D at a use ratio of 2: 1 in one machining pass. When the peak intensities of the two laser light distributions 100C and 100D are different, by increasing the usage ratio of the laser light distribution 100C having the lower peak intensity, the expected processing shape 200C shown in FIG. Compared with the machining shape 200B, the bottom surface of the machining groove can be made uniform in the width direction.

  21 to 23 are diagrams showing a third example of a predicted machining shape calculation method.

  The three laser light distributions 100E, 100F, and 100G shown in FIGS. 21A to 21C have laser light L on one side (left side in the figure), center, and other side (right side in the figure) of the distribution width. The peak position of is biased. The peak intensities of the three laser light distributions 100E, 100F, and 100G are the same.

  Using such laser light distributions 100E, 100F, and 100G, expected processing when laser processing is performed while switching the laser light distributions 100E, 100F, and 100G at a use ratio of 1: 1: 1 within one processing pass. The calculation result of the shape 200D is shown in FIG. As described above, the predicted processed shape 200D shown in FIG. 22 is obtained by adding data obtained by multiplying the three laser light distributions 100E, 100F, and 100G by a usage ratio of 1: 1: 1. Can do.

  In addition, the usage ratio of the laser light distributions 100E, 100F, and 100G is set to 2: 1: 2 in one processing pass, and the expected processing shape 200E when the laser processing is performed while switching the laser light distributions 100E, 100F, and 100G. The calculation results are shown in FIG. When the peak intensities of the three laser light distributions 100E, 100F, and 100G are different, the expected processing shape 200E shown in FIG. Compared to the predicted machining shape 200D shown in Fig. 1, the bottom surface of the machining groove can be made uniform in the width direction.

  Thus, even when the peak intensities of the plurality of laser light distributions are different, an arbitrary processed shape can be obtained by adjusting the usage ratio thereof.

  Further, when laser processing is performed while switching between three or more laser light distributions in one processing pass, it is possible to finely adjust the processing shape by assigning them at an arbitrary ratio.

  Here, for simplicity of explanation, it has been described that the sum of the distributions of the respective laser beams is directly reflected in the machining shape, but in general, the machining rate (R) is proportional to the irradiation fluence (F). Instead, it is known that

R = C ₁ × ln (F / C ₂ )
Note that ln represents a natural logarithm, and C ₁ and C ₂ represent constants.

  FIG. 24 is a log-log graph showing an example of the correspondence relationship between irradiation fluence and processing rate, where the horizontal axis represents the logarithm of irradiation fluence and the vertical axis represents the logarithm of processing rate. Here, as a point to be particularly noted, as can be seen from FIG. 24, there is a threshold value for the irradiation fluence for each workpiece material. If a part of the laser light distribution (light intensity distribution) has an irradiation fluence below the threshold value, that part will not contribute to processing, and there will be a difference from the calculation result of the predicted processing shape by simple addition. It is necessary to pay attention to.

(Step S18: Determination step)
Next, the control unit 30 calculates an error by comparing the predicted machining shape calculated in the predicted machining shape calculation step (step S16) with the target machining shape, and the error is within a preset allowable error range. If it is determined, the process proceeds to the next step S20. On the other hand, if it is determined that the error is not within the allowable error range, the process proceeds to step S26.

(Step S20: Test processing step)
Next, using the test machining workpiece, the test machining workpiece is tested under the machining conditions when the error indicating the difference between the two shapes is determined to be within the allowable error range in the determination step (step S18). Processing.

(Step S22: Process shape measurement step)
Next, the machining shape of the machining groove formed on the test machining workpiece is measured by the machining shape measuring means 72. At this time, when there is no test machining workpiece at the measurement position of the machining shape measuring means 72 (position facing the machining shape measuring means 72), the work table 16 holding the test machining workpiece is moved to the measurement position. Machining shape data (three-dimensional shape data) indicating the machining shape measured by the machining shape measuring means 72 is output to the control unit 30.

(Step S24: Process shape comparison process)
Next, the control unit 30 calculates an error by comparing the machining shape data obtained in the machining shape measurement step (step S22) with the target machining shape data, and the error is within a preset allowable error range. When it is determined that, the process proceeds to step S28. On the other hand, if it is determined that the error is not within the allowable error range, the process proceeds to step S26.

(Step S26: Laser light distribution adjusting step)
In the determination step (step S18), when it is determined that the error indicating the difference between the predicted machining shape calculated in the predicted machining shape calculation step (step S16) and the target machining shape is not within the allowable error range, or the machining shape In the comparison step (step S24), when it is determined that the error indicating the difference between the machining shape data obtained in the machining shape measurement step (step S22) and the target machining shape data is not within the allowable error range, the control unit 30 functions as a laser light distribution adjusting means, and adjusts the laser light distribution in the liquid jet J so that the error is reduced. Thereafter, the process returns to step S12, and the processing conditions of each part of the apparatus are set (changed) so that the adjusted laser light distribution is realized, and the same processing is repeated. Note that, in the laser light distribution adjustment step, when there are a plurality of laser light distributions corresponding to the target processing shape, the usage ratio of each laser light distribution is also changed.

(Step S28: Main processing step)
In the machining shape comparison process (step S24), when it is determined that the error indicating the difference between the machining shape data obtained in the machining shape measurement process (step S22) and the target machining shape data is within the allowable error range. The control unit 30 performs the main machining process under the machining conditions adjusted so far. When this processing step is performed, the laser light distribution observation device 26 moves to the retracted position.

  In the present machining process, the control unit 30 moves the workpiece W and the machining head 40 that are sucked and held on the holding surface 16a of the work table 16 in the machining feed direction (X direction) (an example of the movement process). The liquid jet J is ejected from the liquid jet ejection nozzle 48 of the machining head 40 toward the workpiece W, and the workpiece W is irradiated with the laser beam L induced by the liquid jet J (an example of a laser beam irradiation step). . As a result, a processed groove having a predetermined depth is formed in the workpiece W along the planned division line without causing film peeling or burrs.

  At this time, the control unit 30 performs laser processing while switching the laser light distribution in the liquid jet J to a plurality of distributions by deflecting the laser light L at high speed by the high speed deflecting means 68 (high speed deflection process and high speed). An example of a deflection control process). Thereby, a target machining shape can be obtained without repeatedly performing machining in one machining pass.

  When the formation of one line of the processing groove is completed, the Y table to which the head unit 22 is attached is indexed in the Y direction, and the processing groove is similarly formed on the next line.

  When the machining grooves are formed along all the planned cutting lines parallel to the X direction, the θ rotation table 34 is rotated by 90 °, and all the machining grooves are formed in the same manner for the lines orthogonal to the previous line.

  As described above, according to the present embodiment, laser processing is performed while switching the laser light distribution in the liquid jet J on the surface of the workpiece W to a plurality of distributions by deflecting the laser light L at high speed by the high-speed deflecting means 68. be able to. As a result, the laser light distribution in the liquid jet J can be actively controlled, and a target machining shape can be obtained without repeating machining in one machining pass.

  Further, in the present embodiment, the surface of the workpiece W so that the machining shape measured by the machining shape measuring means 72 (the machining shape actually machined by the laser light emitted from the machining head 40) approaches the target machining shape. Feedback control for automatically adjusting the laser light distribution in the liquid jet J is performed. Therefore, it is not necessary to manually adjust the laser light distribution and evaluate the machining shape for several cycles in order to obtain the target machining shape. Therefore, it is necessary for laser machining to reduce judgment, labor and time until the target machining shape is obtained. By shortening the time, it is possible to reduce the work man-hours and improve the production efficiency, and to obtain the target machining shape with high accuracy.

  Further, in the present embodiment, the expected machining shape when the workpiece W is machined by the machining head 40 can be calculated based on the laser beam distribution observed by the laser beam distribution observation device 26. The expected machining shape can be easily grasped. In addition, feedback control is performed to adjust the laser light distribution in the liquid jet J on the surface of the workpiece W so that the predicted machining shape approaches the target machining shape, so that the target machining shape can be obtained efficiently in a short time. It becomes.

  In the present embodiment, when a pulse laser is used as the laser light L, it is preferable that the repetition frequency of the pulse laser is sufficiently faster than the switching speed (frequency) of the high-speed deflection means 68.

  In this embodiment, the angle range in which the high-speed deflecting means 68 deflects the laser beam L at high speed is set within the angle range (liquid jet incident angle range) that can be incident on the liquid jet J. Not limited to this, it may be set wider than the liquid jet incident angle range. In this case, when the laser beam L is deflected at high speed by the high-speed deflection unit 68, not only a pattern (laser beam distribution) for causing the laser beam L to enter the liquid jet J but also a pattern for preventing the laser beam L from entering the liquid jet J. (Laser light distribution) can also be included. As a result, the substantial intensity of the laser light L irradiated to the workpiece W can be reduced, so that the machining shape can be controlled more extensively and finely, while the machining shape remains unchanged. The processing rate itself can be controlled according to the presence or absence.

  In the present embodiment, the case where laser processing is performed while switching the laser light distribution in the liquid jet J to a plurality of distributions in one processing pass has been described, but without switching the laser light distribution in one processing pass, The case where laser processing is performed in a state where the laser light distribution is fixed may be included.

  FIG. 25 illustrates a laser processing method in a case where laser processing is performed with a constant laser beam distribution in the liquid jet J in one processing pass (that is, when one type of laser beam distribution is used). It is a conceptual diagram for. Hereinafter, a description will be given with reference to FIG.

  First, as shown in (a) of FIG. 25, when one machining shape is selected from a plurality of machining shapes (machining grooves) preset in the laser machining apparatus 10, the control unit 30 The selected machining shape is set as the target machining shape. Here, it is assumed that a machining shape indicating a rectangular machining groove which is a portion surrounded by a broken line in the drawing is selected and set as a target machining shape.

  Next, as shown in (b) and (c) of FIG. 25, the control unit 30 performs processing conditions for each part of the apparatus so that a laser light distribution (target laser light distribution) corresponding to the target processing shape is realized. Set. FIG. 25 (b) shows projection data obtained by projecting the target laser light distribution in a direction orthogonal to the machining feed direction. FIG. 25C is a plan view of the target laser light distribution, where the horizontal axis represents the position in the direction orthogonal to the machining feed direction, and the vertical axis represents the position in the machining feed direction. In FIG. 25 (b), the high density part (dark part) in the figure corresponds to the part with high laser light intensity, and the low density part (bright part) in the figure is the part with low laser light intensity. It corresponds to. The same applies to (g) of FIG.

  Next, the laser light distribution in the liquid jet J is observed by the laser light distribution observation device 26. FIG. 25D shows projection data (actual measurement value) of the laser light distribution observed by the laser light distribution observation device 26. In addition, the broken line in a figure is the projection data (target value) of the target laser beam distribution shown to (b) of FIG.

  Next, the control unit 30 calculates an error by comparing the laser light distribution observed by the laser light distribution observation device 26 with the target laser light distribution, and whether or not the error is within a preset allowable error range. Determine whether. When it is determined that the error is not within the allowable error range, the control is performed so that the error becomes small (that is, the laser light distribution observed by the laser light distribution observation device 26 approaches the target laser light distribution). After adjusting the laser light distribution, the unit 30 repeats the same process until the error is determined to be within the allowable range.

  On the other hand, as shown in FIG. 25 (d), the laser light distribution observed by the laser light distribution observation device 26 is approximate to the target laser light distribution, and the error due to the comparison between the two is within the allowable error range. When it is determined, the test machining is performed on the test machining workpiece under the machining conditions when the determination is performed.

  Next, the machining shape (machining groove) formed on the test machining workpiece is measured by the machining shape measuring means 72. FIG. 25E shows an example of the measurement result of the machining shape measured by the machining shape measuring means 72. The solid line in the figure indicates the machining shape (actual value) measured by the machining shape measuring means 72, and the broken line in the figure indicates the target machining shape (measurement value).

  Next, the control unit 30 compares the machining shape measured by the machining shape measuring means 72 with the target machining shape, calculates an error, and determines whether the error is within a preset allowable error range. To do. When it is determined that the error is within the allowable error range, this processing step is performed under the processing conditions when the determination is made.

  On the other hand, as shown in FIG. 25 (e), the error between the machining shape measured by the machining shape measuring means 72 and the target machining shape is not approximate, and the error due to the comparison between the two is not within the allowable error range. When the determination is made, the control unit 30, based on the result of comparing the machining shape measured by the machining shape measuring unit 72 and the target machining shape, the position where the error is larger as the error between the two is larger. In comparison, the target laser light distribution is adjusted so that the laser light intensity becomes relatively large. An example of the target laser light distribution after adjustment is shown in FIGS. In the case shown in (e) of FIG. 25, the error at the position on the right side in the drawing is relatively larger than the position on the left side in the drawing. Therefore, as shown in (f) and (g) in FIG. The target laser beam distribution is adjusted so that the laser beam intensity at the middle right position is relatively large.

  In this way, after adjusting the target laser light distribution, the control unit 30 repeats the same processing until it is determined that the error between the machining shape measured by the machining shape measuring unit 72 and the target machining shape is within the allowable range. Do.

  That is, as shown in (h) of FIG. 25, the adjustment was performed until the laser light distribution (measured value) observed by the laser light distribution observation device 26 approaches the corrected target laser light distribution (target value). Thereafter, further test machining is performed, and adjustment is performed until the machining shape (actual measurement value) measured by the machining shape measuring means 72 approaches the target machining shape (measurement value), as shown in FIG. . When it is determined that the error between the machining shape measured by the machining shape measuring unit 72 and the target machining shape is within the allowable error range, the machining process is performed under the machining conditions when the determination is performed. carry out.

  As described above, even when laser processing is performed in a state where the laser light distribution in the liquid jet J is constant in one processing pass, the processing shape measured by the processing shape measuring means 72 is close to the target processing shape. The feedback control for automatically adjusting the laser light distribution in the liquid jet J on the surface of the workpiece W is performed. Therefore, it is not necessary to manually adjust the laser light distribution and evaluate the machining shape for several cycles in order to obtain the target machining shape. Therefore, it is necessary for laser machining to reduce judgment, labor and time until the target machining shape is obtained. By shortening the time, it is possible to reduce the work man-hours and improve the production efficiency, and to obtain the target machining shape with high accuracy.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. Hereinafter, description of parts common to the first embodiment will be omitted, and description will be made focusing on characteristic parts of the present embodiment.

  FIG. 26 is a schematic diagram illustrating a configuration of a laser processing apparatus 10A according to the second embodiment. In FIG. 26, components that are the same as or similar to those in FIG. 1 are assigned the same reference numerals, and descriptions thereof are omitted.

  As shown in FIG. 26, the laser processing apparatus 10A according to the second embodiment is provided with a reflection mirror 37 and a spatial light phase modulator 70 between the laser oscillator 14 and the high-speed deflection means 68. This is different from the first embodiment.

  The reflection mirror 37 reflects the laser light L output from the laser oscillator 14 toward the spatial light phase modulator 70.

  The spatial light phase modulator 70 is means for adjusting (modulating) the phase of the laser beam L incident from the laser oscillator 14 via the reflection mirror 37, and its operation is controlled by the control unit 30. As the spatial light phase modulator 70, for example, an LCOS-SLM (Liquid Crystal on Silicon-Spatial Light Modulator) can be preferably employed. The laser light L whose phase has been adjusted by the spatial light phase modulator 70 is incident on the high-speed deflection means 68. Since the configuration and operation of the spatial light phase modulator 70 are known, a specific description is omitted here.

  FIG. 27 is a diagram for explaining the effect of phase adjustment by the spatial light phase modulator 70. FIG. 27 shows a state in which the laser light L condensed by the condenser lens 42 is incident on the liquid jet J. FIG. 27A shows the case where the spatial light phase modulator 70 is not provided (no phase adjustment). b) shows the case where the spatial light phase modulator 70 is provided (with phase adjustment).

  As shown in FIG. 27A, when the laser light L is condensed so as to be incident on the liquid jet J by the condenser lens 42, an aberration may occur in the laser light L. On the other hand, in this embodiment, as shown in FIG. 27B, the phase of the laser light L is adjusted by the spatial light phase modulator 70, so that the laser light L at the time of incidence on the liquid jet J is adjusted. Aberration can be corrected. Thereby, the laser beam distribution in the liquid jet J at the machining position (the surface of the workpiece W) can be adjusted with high accuracy.

  As described above, according to the laser processing apparatus 10A according to the second embodiment, the spatial light phase modulator 70 adjusts the phase of the laser light L, thereby adjusting the laser light distribution in the liquid jet J and processing shape. Can be adjusted in more detail.

  Further, the laser light L can be branched into a plurality of laser lights by adjusting the phase of the laser light L by the spatial light phase modulator 70. Accordingly, it is possible to switch the pattern including a pattern (laser light distribution) obtained by branching the laser beam L into a plurality of laser beams, and it is possible to form an arbitrary processed shape in detail and efficiently.

(Third embodiment)
Next, a third embodiment of the present invention will be described. Hereinafter, description of parts common to the above-described embodiments will be omitted, and description will be made focusing on characteristic parts of the present embodiment.

  FIG. 28 is a schematic diagram showing the configuration of a laser processing apparatus 10B according to the third embodiment. In FIG. 28, components that are the same as or similar to those in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  As shown in FIG. 28, the laser processing apparatus 10B according to the third embodiment is different from the first embodiment in that a workpiece surface state measuring unit 74 is provided at a position adjacent to the processing head 40. .

  The workpiece surface state measuring unit 74 is a unit that measures the state of the surface of the workpiece W. The workpiece surface state measuring means 74 is preferably a non-contact type that performs measurement without contacting the surface of the workpiece W. For example, a sensor using a spectral interference laser displacement meter, a knife edge method, a camera, or the like is employed. Can do. The workpiece surface state measuring means 74 may be any device that can measure the surface state of the workpiece W (for example, the height of the surface of the workpiece W, the reflection intensity, etc.). The workpiece surface state measuring means 74 is not limited to a non-contact type that performs measurement without contacting the surface of the workpiece W, and measures the surface state of the workpiece W by contacting the surface of the workpiece W. May be.

  According to such a configuration, the position of the structure (for example, a metal pad) on the planned cutting line on the surface of the workpiece W can be detected by measuring the surface state of the workpiece W by the workpiece surface state measuring unit 74. it can. The position of the structure on the planned cutting line thus detected is stored in a memory unit (not shown). Thereby, when laser processing is performed, it becomes possible to change a processing condition according to the presence or absence of the structure on a cutting scheduled line. That is, cutting is performed by performing laser processing while switching the laser light distribution in the liquid jet J to a plurality of distributions so that the intensity of the laser light L is higher in the portion with the structure than in the portion without the structure. Even when there is a structure on the planned line (that is, when the machining rate is not uniform for the same scheduled cutting line), the machining depth can be made uniform (a uniform depth in the width direction). Become. That is, by changing the intensity of the substantial laser beam L irradiated to the workpiece W according to the position of the structure measured by the workpiece surface state measuring means 74, the machining rate of the entire machining shape such as the machining groove can be changed. It becomes possible to keep it uniform.

  FIGS. 29 and 30 are diagrams for explaining the effect of the third embodiment. When the machining groove K is formed on the workpiece W along the planned cutting line, depending on the presence or absence of structures on the planned cutting line. It shows an example of the relationship between the irradiation light quantity (laser beam intensity), the processing rate, and the processing depth when different materials (hardness) exist. Here, it is assumed that the workpiece material G1 has higher hardness than the workpiece material G2. Further, as shown in FIG. 8, the laser processing is performed while sequentially changing the peak position Q of the laser light L in the liquid jet J in a direction orthogonal to the processing feed direction M. In addition, hardness here means the difficulty of being processed with respect to the processing conditions to be used (the wavelength of the laser beam L, etc.).

  FIG. 29 shows a case where the processing conditions are constant regardless of the presence or absence of structures on the planned cutting line. As shown in (a) and (b) of FIG. 29, when the irradiation light quantity of the laser light L irradiated on the surface of the workpiece W is constant along the processing feed direction M, it is shown in (c) of FIG. As described above, the machining rate varies depending on the difference between the workpiece material G1 and the workpiece material G2. For this reason, as shown in FIG. 29 (d), the machining depth in the machining groove K differs between the workpiece material G1 and the workpiece material G2, resulting in a non-uniform machining depth as a whole.

  FIG. 30 shows a case where the machining conditions are changed according to the presence or absence of structures on the planned cutting line. As shown in FIGS. 30A and 30B, when the workpiece material G2 has a larger interval in the machining feed direction at the peak position Q of the laser beam L in the liquid jet J than the workpiece material G1, The workpiece material G2 has a smaller amount of laser light L irradiated onto the surface of the workpiece W than the workpiece material G1. In this case, as shown in FIG. 30C, the work material G2 has a higher processing rate than the work material G1. Therefore, as shown in FIG. 30 (d), the machining depth in the machining groove K is the same depth for the workpiece material G1 and the workpiece material G2, and the machining depth is uniform throughout. In addition, it is preferable that the irradiation light quantity of the laser beam L irradiated on the surface of the workpiece W is adjusted according to the state of the surface of the workpiece W measured by the workpiece surface state measuring unit 74.

  As described above, according to the laser processing apparatus 10B according to the third embodiment, the substantial intensity of the laser light L irradiated to the workpiece W is changed according to the position of the structure measured by the workpiece surface state measuring unit 74. By changing it, it becomes possible to obtain a desired processed shape.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the scope of the present invention. .

  DESCRIPTION OF SYMBOLS 10 ... Laser processing apparatus, 12 ... Laser power supply, 14 ... Laser oscillator, 16 ... Work table, 16a ... Holding surface, 18 ... Work table moving part, 20 ... Liquid supply means, 22 ... Head unit, 26 ... Observation of laser light distribution Device: 30 ... Control unit, 32 ... X table, 34 ... theta rotation table, 36 ... deflection unit, 37 ... reflection mirror, 38 ... beam shape shaping means, 40 ... processing head, 42 ... condensing lens, 44 ... head body , 46 ... Liquid chamber, 48 ... Liquid jet injection nozzle, 50 ... Window part, 52 ... Shielding plate, 54 ... Liquid removing means, 56 ... Imaging lens, 58 ... Photo detector, 60 ... Body part, 64 ... Monitor, 68 ... High-speed deflection means, 70 ... Spatial light phase modulator, 72 ... Work shape measurement means, 74 ... Work surface state measurement means, L ... Laser light, J ... Liquid jet

Claims (10)

A laser oscillator;
A processing head for irradiating a workpiece while guiding a laser beam output from the laser oscillator with a liquid jet;
Moving means for relatively moving the processing head and the workpiece;
Machining shape measuring means for measuring a machining shape formed by the machining head;
A laser beam for adjusting a laser beam distribution in the liquid jet on the laser beam irradiation surface of the workpiece based on a comparison between the machining shape measured by the machining shape measuring unit and a target machining shape of the workpiece. Distribution adjustment means;
A laser processing apparatus comprising: The laser light distribution adjusting unit calculates an error by comparing the machining shape measured by the machining shape measuring unit with a target machining shape of the workpiece, and when the error is outside an allowable error range. Adjusting the laser light distribution based on the error;
The laser processing apparatus according to claim 1. Comprising high-speed deflection means for deflecting the laser beam at high speed on the way from the laser oscillator to the machining head;
The laser beam distribution adjusting unit changes the deflection condition of the high-speed deflection unit based on a comparison between the machining shape measured by the machining shape measuring unit and a target machining shape of the workpiece. Adjust the distribution,
The laser processing apparatus according to claim 1. Comprising low-speed deflection means for deflecting the laser beam output from the laser oscillator toward the machining head;
The high-speed deflection means performs a higher-speed deflection and a narrower range of deflection than the low-speed deflection means.
The laser processing apparatus according to claim 3. The high-speed deflection means is an acousto-optic deflection element;
The laser processing apparatus according to claim 3 or 4. Laser light distribution observation means for observing the laser light distribution;
Based on the laser light distribution observed by the laser light distribution observation means, an expected machining shape calculation means for calculating an expected machining shape when the workpiece is machined by the machining head, and
The laser light distribution adjusting means adjusts the laser light distribution based on a comparison between an expected machining shape calculated by the expected machining shape calculating means and a target machining shape of the workpiece.
The laser processing apparatus of any one of Claim 3 to 5. The laser light distribution adjusting unit calculates an error by comparing the predicted machining shape calculated by the predicted machining shape calculation unit with a target machining shape of the workpiece, and the error is outside an allowable error range. Adjusts the laser light distribution based on the error,
The laser processing apparatus according to claim 6. By changing the deflection condition of the high-speed deflection means when irradiating the workpiece with the laser light from the machining head while relatively moving the machining head and the workpiece by the moving means. , Comprising high-speed deflection control means for switching the laser light distribution to a plurality of distributions,
The predicted machining shape calculation means is based on the plurality of distributions of the laser light observed by the laser light distribution observation means, and is changed by the machining head while switching the laser light distribution to the plurality of distributions by the high-speed deflection control means. Calculate an expected machining shape when machining the workpiece.
The laser processing apparatus according to claim 6 or 7. The high-speed deflection control unit is configured so that the peak position of the laser beam in the laser beam distribution is scanned in a direction orthogonal to the relative movement direction of the processing head and the workpiece. Change the deflection condition,
The laser processing apparatus according to claim 8. A laser light irradiation step of irradiating a workpiece with laser light guided by a liquid jet;
A moving step of relatively moving the liquid jet and the workpiece;
A machining shape measuring step for measuring a machining shape formed by the laser beam;
Laser light distribution for adjusting the laser light distribution in the liquid jet on the laser light irradiation surface of the workpiece based on a comparison between the machining shape measured in the machining shape measurement step and the target machining shape of the workpiece. Adjustment process;
A laser processing method comprising: