JP2005125357A - Laser beam machining method and laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining method by which the number of times for moving a workpiece is reduced to shorten time for machining. <P>SOLUTION: The laser beam machining method includes steps of: (a) positioning a laser beam condensing lens and a workpiece so that the center axis of the lens passes through one grating point of the equilateral triangular gratings defined on the surface of the workpiece; (b) making the laser beam incident on the lens, changing the advancing direction of the laser beam before the incidence to the lens, and making the laser beam incident on the surface of the workpiece; (c) positioning the lens and the workpiece so that the center axis of the lens passes through another grating point of the equilateral triangular gratings defined on the surface of the workpiece; and (d) implementing the steps (b) and (c) repeatedly more than once. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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 that perform processing by positioning a lens and an object to be processed.

  2. Description of the Related Art Laser processing apparatuses that perform processing by swinging the traveling direction of a laser beam emitted from a laser light source with a galvano scanner, converging the laser beam emitted from the galvano scanner with an fθ lens, and irradiating the object to be processed are widely used. The object to be processed is held on an XY stage that moves the object to be processed in parallel to the surface to be processed. Such a laser processing apparatus is disclosed in Patent Document 1, for example.

  The fθ lens emits the incident laser beam in a direction parallel to the central axis of the fθ lens. The object to be processed is arranged so that the laser beam emitted from the fθ lens is perpendicularly incident on the surface to be processed. Therefore, the laser beam emitted from the fθ lens cannot be applied to an area on the processing surface that exceeds the size of the fθ lens.

  In order to process the entire region to be processed, the XY stage is stopped at a certain position, the laser beam is oscillated with a galvano scanner, the region that can be irradiated with laser is processed, the XY stage is moved, and the unprocessed region can be laser irradiated The process of moving to a position and processing an unprocessed area is repeated.

JP 2001-71167 A

  The total processing time is a cumulative time for irradiating the laser beam to the processing part by moving the traveling direction of the laser beam with the galvano scanner, or the time for moving the processing object on the XY stage.

  In particular, the movement of the XY stage takes time because acceleration / deceleration cannot be performed instantaneously. In order to shorten the processing time, it is preferable to reduce the number of movements of the XY stage.

  An object of the present invention is to provide a laser processing method and a processing apparatus that can reduce the processing time and reduce the processing time.

  According to one aspect of the present invention, (a) a lens that converges a laser beam passes through one lattice point of a regular triangular lattice defined on the surface of the workpiece, A step of positioning the object to be processed; (b) a laser beam is incident on the lens, a traveling direction of the laser beam before being incident on the lens is changed, and a laser beam is incident on the surface of the object to be processed. And (c) positioning the lens and the workpiece so that a central axis of the lens passes through another lattice point of the equilateral triangular lattice defined on the surface of the workpiece. There is provided a laser processing method comprising: a step; and (d) a step of repeatedly performing the step (b) and the step (c) a plurality of times.

  According to another aspect of the present invention, a laser light source that emits a laser beam, a beam scanner that changes the traveling direction of the laser beam emitted from the laser light source under external control, and an object to be processed are held. And a holder that can move the object to be processed under the control of the outside, and a workpiece that is held on the holder by converging the laser beam that has been swung in the traveling direction by the beam scanner. A lens that is incident on the surface of the object, and a control device that controls the beam scanner and the holding table. The control device includes: (a) the central axis of the lens is on the surface of the workpiece. A step of controlling the holding table so as to pass one lattice point of the defined equilateral triangular lattice; and (b) controlling the beam scanner to swing the traveling direction of the laser beam, Laser beam on the surface And (c) controlling the holding table so that the central axis of the lens passes through other lattice points of the equilateral triangular lattice defined on the surface of the workpiece. (D) There is provided a laser processing apparatus for controlling the beam scanner and the holding table so that a step of repeatedly performing the step (b) and the step (c) a plurality of times is executed.

  The number of times that the lens and the object to be processed are positioned can be reduced as compared with the prior art, and the laser beam can be irradiated to the entire processing area. Since the number of movements of the workpiece is reduced, the machining speed can be improved.

  FIG. 1 is a schematic view of a laser processing apparatus according to an embodiment of the present invention. The laser light source 1 emits a pulse laser beam. As the laser light source 1, for example, a carbon dioxide laser or an Nd: YAG laser that includes a wavelength conversion unit and generates harmonics can be used.

  The laser beam emitted from the laser light source 1 is reflected by the folding mirror 2 and enters the galvano scanner 3. The galvano scanner 3 can swing the traveling direction of the laser beam in a two-dimensional direction. The control device 7 controls the galvano scanner 3 so as to swing the traveling direction of the laser beam in a desired direction at a desired timing.

  The laser beam emitted from the galvano scanner 3 enters the fθ lens 4 and converges. The fθ lens 4 emits the incident laser beam aligned in a direction parallel to the central axis of the fθ lens 4.

  The laser beam emitted from the fθ lens 4 enters the workpiece 5. The workpiece 5 is disposed so that the laser beam emitted from the fθ lens 4 is incident on the surface to be processed perpendicularly.

  The workpiece 5 is, for example, a printed wiring board in which an inner wiring layer is embedded in a resin layer or a substrate in which an ITO film is formed on the surface of a glass substrate. The surface of the workpiece 5 is irradiated with laser to perform processing for forming holes, grooves, and the like.

  The workpiece 5 is held on the XY stage 6. The XY stage 6 is used for moving the workpiece 5 in a direction parallel to the surface of the workpiece 5. The control device 7 controls the XY stage 6 so as to move the workpiece 5 to a desired position at a desired timing.

  A plurality of unit regions are defined on the surface of the workpiece 5. The shape and size of each unit region are set so as to be included in a range in which the galvano scanner 3 can irradiate the laser beam while changing the traveling direction of the laser beam while the XY stage 6 is stopped. Processing is performed by operating the galvano scanner 3 for each unit area. When processing of a certain unit region is completed, the XY stage 6 is moved, and the unprocessed unit region is moved to a position where laser irradiation can be performed. Such a process is repeated and the process over the whole process area is performed.

  Next, with reference to FIG. 2, the unit area | region set with the laser processing method by a present Example is demonstrated. FIG. 2 is a plan view of the workpiece 5 as seen from the line of sight along the central axis of the fθ lens 4 shown in FIG.

A processable region 10 is a region where the entire surface of the lens surface on the incident side of the fθ lens can be scanned by the galvano scanner and the laser can be irradiated. Since the fθ lens is circular, the workable region 10 is circular. The diameter of the workable region 10 is, for example, 56.57 mm, and its area is approximately 2513 mm ² .

  Each unit area is set so as to be included in the processable area 10. Each of the plurality of unit regions defined so as to cover the entire region to be processed is sequentially moved into the processable region 10 for processing.

  In this embodiment, each unit area is set to a regular hexagon. All unit areas are congruent. The unit area is set to be congruent with the regular hexagon 11 inscribed in the outer periphery of the workable area 10 at the maximum. Hereinafter, a case where the unit area is congruent with the regular hexagon 11 will be described. As will be described later with reference to FIG. 3, the unit regions can be arranged without overlapping and without gaps to cover the entire region to be processed.

  In the conventional laser processing method, the unit area is set to be congruent with the square 12 inscribed in the outer periphery of the processable area 10. These unit areas can also be arranged without overlapping and without any gaps to cover the entire work area.

The unit region of this embodiment congruent with the regular hexagon 11 has a larger area than the unit region of the prior art congruent with the square 12. When the diameter of the workable region 10 is, for example, 56.57 mm, one side of the regular hexagon 11 is about 28.29 mm and the area is about 2079 mm ² . A ratio obtained by dividing this area by the area of the workable region 10 is about 83%. On the other hand, the length of one side of the square 12 is 40.00 mm, the area is 1600 mm ² , and the ratio divided by the area of the workable region 10 is about 64%. In the laser processing method of this embodiment, the fθ lens is used efficiently.

  If each unit area is widened, the number of unit areas necessary to cover the entire processing area can be reduced, so that the number of operations of the XY stage for moving the workpiece is reduced. By reducing the number of operations of the XY stage, the processing time can be shortened.

  Next, an example of a method for processing the entire processing region will be described with reference to FIG. The workpiece 5 is positioned and held at a predetermined position on the XY stage 6. A region to be processed 20 is defined on the surface of the workpiece 5. A portion to be processed defined in the processing region 20 is irradiated with a laser to perform processing such as drilling.

  On the surface of the workpiece 5, congruent regular hexagonal unit regions 11-1 to 11-26 are defined. Circles 10-1, 10-2, etc. indicated by alternate long and short dash lines are circumscribed on the unit regions 11-1, 11-2, etc., respectively. All these circles are congruent. When each unit region is processed, the inside of the circumscribed circle of the unit region corresponds to the inside of the processable region 10 shown in FIG. That is, when each unit region is processed, laser irradiation is possible by operating the galvano scanner inside the circumscribed circle.

  The centers of the circles 10-1, 10-2, etc. are the center points 13-1, 13-2, etc. The center points 13-1 to 13-26 coincide with the centers (intersection points of regular hexagonal diagonal lines) of the unit regions 11-1 to 11-26.

  The unit areas 11-1 to 11-26 are arranged in four rows with no overlap and no gap. The unit areas 11-1 to 11-6 are the first line, the unit areas 11-7 to 11-13 are the second line, the unit areas 11-14 to 11-19 are the third line, and the unit area 11-20. ~ 11-26 make the 4th line. The region to be processed 20 is included in the region covered with the 26 unit regions 11-1 to 11-26. Two unit regions adjacent to each other are in contact with each other so as to share one side. The center point of the unit area in a row is located on a straight line connecting the center points of the unit areas at both ends of the row. The straight lines connecting the center points of the unit areas at both ends of each row are parallel to each other.

  A processing method according to this embodiment will be described. First, the XY stage 6 is moved so that the central point 13-1 of the unit region 11-1 is positioned on the central axis of the fθ lens (so that the central axis of the fθ lens passes through the central point 13-1). Operate to position the workpiece 5. Next, while the XY stage 6 is stopped, the portion to be processed in the unit region 11-1 is irradiated with laser while operating the galvano scanner.

  When the laser irradiation into the unit region 11-1 is completed, the XY stage 6 is moved in the direction of a straight line connecting the center points 13-1 and 13-6, and the unit region 11-1 is placed on the central axis of the fθ lens. The center point 13-2 of the unit region 11-2 adjacent to is located. While the XY stage 6 is stopped, the portion to be processed in the unit region 11-2 is irradiated with laser while operating the galvano scanner.

  Subsequently, the remaining unit regions 11-3 to 11-6 in the first row are processed while moving the XY stage 6 in the direction of a straight line connecting the center points 13-1 and 13-6. When the processing of the unit region 11-6 including the edge of the region to be processed is finished, the unit region 11-7 adjacent to the unit region 11-6 and the end of the unit regions 11-7 to 11-13 in the second row The XY stage 6 is moved so that the central axis of the fθ lens is positioned on the center point 13-7, and the unit region 11-7 is processed.

  Next, the remaining unit regions 11-8 to 11-13 in the second row are processed while moving the XY stage 6 in the direction of a straight line connecting the center points 13-7 and 13-13. The direction of movement of the XY stage 6 when processing the second row is opposite to that when processing the first row.

  Thereafter, the unit areas 11-14 to 11-26 are sequentially processed in the same manner. As described above, when the processing of a certain unit region is completed, the processing of the unit region adjacent to the unit region is repeated to complete the processing of the entire region to be processed 20. In other words, when the center of the fθ lens is positioned on a certain center point and the processing is completed, the processing is repeated by moving the center axis of the fθ lens on the center point closest to the center point. The number of movements of the XY stage is 25 times from the start of processing of the unit region 11-1 to the end of processing of the unit region 11-26. The arrow in the figure indicates the moving direction of the central axis of the fθ lens on the surface of the workpiece. During the movement of the XY stage, the laser is not incident on the region to be processed, for example, by stopping the emission of the laser beam from the laser light source.

  Note that square unit regions according to the conventional technique are squares 12-1, 12-2, etc., indicated by broken lines. Each of these is congruent with the square inscribed in the circle 10-1. The to-be-processed area | region 20 is contained in 28 square unit area | regions 12-1, 12-2 etc. which were arranged in 4 rows and 7 columns without an overlap and a clearance gap.

  When processing by the conventional technique, the center of the square unit area (intersection of diagonal lines) may be positioned on the central axis of the fθ lens and the unit area may be processed. By processing 28 square unit regions, processing of the entire processing region 20 can be completed. The number of movements of the XY stage is 27 times.

  The area of two inscribed regular hexagons of the circle 10-1 can be processed by the method of this embodiment with one movement of the XY stage. On the other hand, the method of the prior art can process only the area of two inscribed squares of the circle 10-1.

  Thus, in the processing method of this embodiment, the area of the unit region is larger than that of the conventional processing method, and the number of movements of the XY stage is reduced, so that the processing time can be shortened.

  Although the example which processes the unit area | region adjacent to each other was demonstrated, the order which processes a unit area is not restricted to this. If a certain unit region is processed, then a unit region that is not adjacent to the unit region may be processed.

  In the method of sequentially processing unit regions adjacent to each other, the movement distance of the XY stage each time can be the distance between the centers of adjacent unit regions. Therefore, the total movement distance of the XY stage when all the unit areas 11-1 to 11-26 are processed can be minimized.

  All unit areas need not be congruent. For example, the region 30 indicated by hatching in the drawing exists in the circumcircle of the unit region 11-25 and also exists in the circumcircle of the unit region 11-26.

  Therefore, the area obtained by removing the area 30 from the unit area 11-25 may be the 25th unit area, and the area obtained by adding the area 30 to the unit area 11-26 may be the 26th unit area. By locating the center axis of the fθ lens on the center point 13-25, the 25th unit area can be processed. Next, the central axis of the fθ lens is positioned on the center point 13-26, and the 26th unit area can be processed.

  As described above, an area that is commonly included in a circumscribed circle of one unit area and a circumscribed circle of another unit area is processed when one unit area is processed, but the other unit area is It may be processed when processed.

  Next, referring to FIG. 4A, how the center point (that is, the intersection of the center axis of the fθ lens and the processing surface when processing each unit area) is positioned on the processing surface. Explain what you are doing. FIG. 4A shows the unit areas 11-1, 11-2, 11-12, and 11-13 shown in FIG.

  Center points 13-1, 13-2, 13-12, and 13-13 at which the central axis of the fθ lens is located when processing each unit region are located on lattice points of a regular triangular lattice. The lattice spacing of the equilateral triangular lattice coincides with the square root of 3, where the radius of the circle 10-1 is 1. Hereinafter, the unit of length will be described assuming that the radius of a circle indicating the outer periphery of the workable region of the fθ lens is 1.

  Each unit region is congruent with a regular hexagon defined by a perpendicular bisector connecting a lattice point having a regular triangular lattice and each of six lattice points closest to the lattice point.

  In the case of the prior art, the central axis of the fθ lens is located on a lattice point of a square lattice formed by the center of the square unit region. The lattice spacing of the square lattice is the square root of 2.

  Next, with reference to FIG. 4B, a modified example in which processing is performed by arranging an fθ lens on a lattice point of a regular triangular lattice whose lattice interval is shorter than the square root of 3 so that the central axis is located will be described. To do.

  In FIG. 4B, center points 13-1a to 13-4a are defined on lattice points of an equilateral triangular lattice defined on the surface to be processed and having a lattice interval shorter than the square root of 3. Regions that can be processed by positioning the central axis of the fθ lens on the respective center points 13-1a to 13-4a are inside the circles 10-1a to 10-4a, respectively. Note that these circles are the same as the circle 10-1 in FIG.

  The regular hexagonal unit regions 11-1a to 11-4a that are congruent to each other are arranged in two rows and two columns with no overlap and no gap, as in the unit region of FIG. The center of each unit region coincides with the center points 13-1a to 13-4a. For the sake of explanation, only four unit regions and lattice points are illustrated.

  Each unit region is congruent with a regular hexagon defined by a perpendicular bisector connecting a lattice point with a regular triangular lattice and each of the six lattice points closest to the lattice point.

  Corresponding to the lattice spacing being shorter than the square root of 3, the unit regions 11-1a and the like are smaller than the regular hexagon inscribed in the circle 10-1a. The shorter the lattice interval, the smaller the area of the unit region.

  If the lattice interval is longer than 1.520 (that is, longer than 1.520 times the radius of the circle indicating the outer periphery of the workable region of the fθ lens), this unit region is inscribed in the circle 10-1a. Can be wider than a square. Therefore, the number of unit regions required for processing the entire region to be processed can be reduced as compared with the prior art. By reducing the number of movements of the XY stage, the processing time can be shortened.

  This value 1.520 is derived as follows. For a circle of radius 1, the area of the inscribed square is 2.000, the area of the inscribed regular hexagon is about 2.598, and the area of the inscribed square is about 76.98% of the area of the inscribed regular hexagon. It is. When the area of the inscribed regular hexagon of the circle of radius x is equal to the area of the inscribed square of the circle of radius 1, x is about 0.8774 (the square root of 0.7698).

  When a regular hexagon inscribed in a circle with radius 1 is laid, the lattice spacing of the regular triangular lattice formed by the center of the regular hexagon becomes the square root of 3, so when a regular hexagon inscribed in a circle with radius x is laid Further, the lattice spacing of the regular triangular lattice formed by the center of the regular hexagon is about 1.520 which is x times the square root of 3.

  When the unit area is smaller than the regular hexagon inscribed in the workable area of the fθ lens as described above, the center of the unit area may not be positioned on the lattice point (that is, on the central axis of the fθ lens). .

  In addition, the unit regions may not be set to the same regular hexagon. Each unit region may be set to an arbitrary shape and size as long as it is included in the processable region of the fθ lens arranged on each lattice point.

  As will be described with reference to FIG. 5, the lattice interval cannot be longer than the square root of 3. In FIG. 5, center points 13-1b to 13-4b are arranged on lattice points of a regular triangular lattice defined on the surface to be processed and having a lattice interval longer than the square root of 3. A region that can be processed by positioning the central axis of the fθ lens on each of the center points 13-1b to 13-4b is the inside of the circles 10-1b to 10-4b. For example, a gap area that is not included in the workable area of the fθ lens arranged on any lattice point is generated, such as a hatched area 40. Such a region cannot be processed. Therefore, a method of making the lattice interval longer than the square root of 3 cannot be adopted.

  On the other hand, if the fθ lens is moved so that the central axis is positioned on a lattice point of a regular triangular lattice having a lattice interval equal to or less than the square root of 3, an arbitrary region in the region to be processed becomes any lattice point. It can be included in the workable area of the fθ lens with the central axis positioned above (that is, the workable area is covered by the workable area of the fθ lens without any defects).

  Although the case where the laser beam is a pulse laser beam has been described, processing using a continuous wave laser beam emitted from a semiconductor laser or the like may be performed.

  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 an Example. It is a top view of the processing target object for demonstrating a unit area | region. It is a top view of the process target object for demonstrating the method of processing the whole to-be-processed area | region. It is a top view of the processed object which shows arrangement | positioning of the intersection of the center axis | shaft of f (theta) lens, and a to-be-processed surface in the laser processing method by an Example. It is a top view of the processing target object which shows arrangement | positioning of the intersection of the central axis of an f (theta) lens, and a to-be-processed surface in the laser processing method by a modification. It is a top view of the processed object which shows arrangement | positioning of the intersection of the center axis | shaft of an f (theta) lens, and a to-be-processed surface in the laser processing method by a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 2 Folding mirror 3 Galvano scanner 4 f (theta) lens 5 Work object 6 XY stage 7 Control apparatus 10 Processable area | region 11 (Inscribed in the processable area | region 10) Regular hexagon 12 (Inscribed in the processable area | region 10) Square 11 -1 to 11-26 unit areas 10-1, 10-2 (corresponding to the outer periphery of the workable area including the unit area) 13-1 to 13-26 (corresponding to the outer periphery of the workable area including the unit area) Center point of circle 20 Work area

Claims (5)

(A) Positioning the lens and the processing object so that the central axis of the lens for converging the laser beam passes through one lattice point of a regular triangular lattice defined on the surface of the processing object When,
(B) causing the laser beam to enter the lens, swinging the traveling direction of the laser beam before entering the lens, and causing the laser beam to enter the surface of the workpiece;
(C) positioning the lens and the processing object so that a central axis of the lens passes through other lattice points of the equilateral triangular lattice defined on the surface of the processing object;
(D) A laser processing method including a step of repeatedly performing the step (b) and the step (c) a plurality of times. The interval between the lattice points of the regular triangular lattice is set to a length that allows the laser beam to be incident on the surface of the workpiece without repeating the steps (b) and (c). The laser processing method according to claim 1. In the step (c), the lens passes through one of the six lattice points closest to the lattice point through which the central axis of the lens passes at the end of the step (b). The laser processing method according to claim 1, wherein positioning between the workpiece and the workpiece is performed. The position on the surface of the workpiece on which the laser beam is incident in the step (b) is a line connecting the lattice point through which the central axis of the lens passes and each of the six lattice points closest to it. The laser processing method according to claim 1, wherein the laser processing method is limited to the inside and the outer periphery of a regular hexagon defined by a perpendicular bisector of the minute. A laser light source for emitting a laser beam;
A beam scanner that shakes the traveling direction of the laser beam emitted from the laser light source under external control;
A holding table that holds the workpiece and receives the control from the outside to move the workpiece;
A lens that converges a laser beam whose traveling direction is swung by the beam scanner and makes the laser beam incident on the surface of an object to be processed held by the holding table;
A control device for controlling the beam scanner and the holding table, the control device,
(A) controlling the holding table so that the central axis of the lens passes one lattice point of a regular triangular lattice defined on the surface of the workpiece;
(B) controlling the beam scanner to swing the traveling direction of the laser beam and causing the laser beam to enter the surface of the workpiece;
(C) controlling the holding table so that the central axis of the lens passes through other lattice points of the regular triangular lattice defined on the surface of the workpiece;
(D) A laser processing apparatus that controls the beam scanner and the holding table so that a step of repeatedly performing the step (b) and the step (c) a plurality of times is executed.

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