JP2008129535A - Beam distribution device and multi-axis laser irradiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a beam distribution device capable of controlling the deflection efficiency upon distributing a beam. <P>SOLUTION: The beam distribution device includes: an acousto-optical element that changes a propagation direction of an incident laser beam by application of an AC voltage, in which a deflection angle depends on a frequency of the AC voltage applied and the deflection efficiency depends on an amplitude of the AC voltage applied; a driver that accepts a command of an exit direction and applies an AC voltage to the acousto-optical element so as to deflect the laser beam to the commanded direction; and a control device that commands the driver an exit direction from the acousto-optical element. The driver includes a memory area to memorize a physical amount determining the deflection efficiency corresponding to each of a plurality of exit directions. When an exit direction is commanded by the control device, the driver determines a frequency and an amplitude so as to render an exit direction into the commanded direction and to obtain the deflection efficiency corresponding to the exit direction memorized in the memory area, and applies an AC voltage to the acousto-optical element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a beam distribution device that includes an acousto-optic deflector (AOD) and can distribute a beam incident from one direction to a plurality of directions and emit the beam. The present invention also relates to a multi-axis laser irradiation apparatus including such a beam distribution apparatus.

  When forming a via hole in a build-up substrate, the required pulse energy differs depending on the material to be processed. Compared to processing a material with good workability such as an epoxy resin material, processing of a material with poor workability such as copper requires a beam with a large pulse energy.

  For example, when a carbon dioxide laser is used on a buildup substrate in which copper layers are insulated with an epoxy resin layer, and a hole diameter of 100 μm is drilled, the blackened copper layer has a pulse energy of 10 mJ, A pulse laser beam having a pulse width of 15 μsec is incident. Further, in order to process the epoxy resin layer, a pulse laser beam having a pulse energy of 3 mJ and a pulse width of 5 μsec is irradiated.

  Thus, since the pulse energy required for processing differs depending on the material forming the processing object, it is possible to maintain good processing quality when processing a processing object in which a material with good workability and a bad material are mixed. It can be difficult.

  In addition, the number of vias in the build-up board has been steadily increasing as electronic devices have higher functionality and higher density. For this reason, high productivity is desired for the laser drill machine.

  2. Description of the Related Art A two-panel four-axis laser drill device that realizes high-speed processing is known. In a multi-axis laser processing apparatus, a laser beam is branched using, for example, a polarizing plate and a half mirror.

  An acousto-optic deflector (AOD) is known as a deflector that emits an incident laser beam in different directions.

  Various laser devices using an acousto-optic deflector (AOD) have been disclosed (for example, see Patent Document 1). Patent Document 1 describes an invention of a laser apparatus and a laser image recording apparatus using the laser apparatus aiming at preventing side lobes from being generated on an image plane by using an acousto-optic deflector as a soft aperture. .

  When a high-frequency electrical signal (AC voltage) is applied to the acoustooptic deflector (AOD), ultrasonic waves synchronized with the electrical signal are generated in the acoustooptic medium of the acoustooptic deflector (AOD). This ultrasonic wave acts as a diffraction grating, and a part of the incident laser beam is Bragg reflected (acousto-optic effect), deflected and emitted.

  The diffraction angle of the laser beam is proportional to the ultrasonic frequency. By continuously changing the ultrasonic frequency, the diffraction angle can be changed continuously. The frequency of the ultrasonic wave can be controlled by changing the frequency of the electric signal. When no electrical signal is applied to the acousto-optic deflector, the laser beam is not diffracted.

  The intensity of the laser beam emitted from the acousto-optic deflector (AOD) is generated in the acousto-optic medium in synchronization with the intensity of the incident laser beam and the amplitude of the applied electric signal, and thus the applied electric signal. Depends on the amplitude of the ultrasound.

  FIGS. 8A and 8B are schematic views showing a laser beam emitted from the acousto-optic deflector (AOD) 10.

  Reference is made to FIG.

For example, a pulse laser beam emitted from a carbon dioxide laser and having a circular cross-sectional shape is incident on an acousto-optic deflector (AOD) 10. The incident beam is given a different deflection angle depending on the frequency of the electric signal applied to the acousto-optic deflector (AOD) 10, and is irradiated onto an irradiation surface 1 m away from the acousto-optic deflector (AOD) 10, for example. FIG. 8A shows a case where four shot pulse laser beams are emitted in four different directions. The irradiated surface is indicated by a dotted line. In the drawing, O _{1 to} O ₄ indicate cross sections of a laser beam that is deflected by an acousto-optic deflector (AOD) 10 and is irradiated onto an irradiation surface, as shown in detail in the following diagram.

The deflection angle of the acousto-optic deflector (AOD) 10 is small, and the full angle θ is about 2 °. For this reason, when the laser beam is uniformly deflected in the four directions, the angle θ ₀ between the adjacent deflected laser beams is about 0.66 ° (about 1.15 mrad).

  On the other hand, the spread angle of the carbon dioxide laser beam is, for example, about 2.1 mrad.

  FIG. 8B is a cross-sectional view showing a cross section of the deflected laser beam irradiated on the irradiation surface.

The divergence angle (for example, about 2.1 mrad) of the carbon dioxide laser beam is larger than the angle θ ₀ (about 1.15 mrad) between adjacent deflection laser beams. For this reason, the laser beam deflected by the acousto-optic deflector (AOD) 10 travels in duplicate at the same position in the space, and the region where the beam is incident has an overlapping portion.

  Laser processing performed using the acousto-optic deflector (AOD) 10 is performed by applying an electric signal having a constant amplitude to the acousto-optic deflector (AOD) 10. Adjustment of the laser beam intensity on the beam irradiation surface (processing surface) is performed, for example, by placing an attenuator between the acousto-optic deflector (AOD) 10 and the beam irradiation surface (processing surface). The attenuator is disposed on each optical path of a laser beam that is deflected and emitted in different directions by an acousto-optic deflector (AOD) 10.

JP 09-073057 A

  An object of the present invention is to provide a beam distribution device capable of controlling deflection efficiency in beam distribution.

  Another object of the present invention is to provide a multi-axis laser irradiation apparatus capable of controlling the deflection efficiency in beam distribution.

  According to one aspect of the present invention, an alternating voltage is applied to change the traveling direction of the incident laser beam, the deflection angle depends on the frequency of the applied alternating voltage, and the deflection efficiency is applied. An acoustooptic device that depends on the amplitude of the ac voltage, a driver that applies an ac voltage to the acoustooptic device so as to deflect the laser beam in the commanded direction by commanding the emission direction, and the driver And a control device that commands an emission direction from the acousto-optic element, wherein the driver includes a storage area that stores a physical quantity that determines deflection efficiency in association with each of a plurality of emission directions, and the control When the emission direction is commanded from the apparatus, the emission direction becomes the commanded direction, and the deflection efficiency becomes the deflection efficiency associated with the emission direction stored in the storage area. To, to determine the frequency and amplitude, the beam allocation apparatus is provided for applying an AC voltage to the acousto-optic device.

  Further, according to another aspect of the present invention, when an alternating voltage is applied, the traveling direction of the incident laser beam is changed, the deflection angle depends on the frequency of the applied alternating voltage, and the deflection efficiency is By instructing the acoustooptic device that depends on the amplitude of the applied AC voltage, the emission direction, and the physical quantity that determines the deflection efficiency, the laser beam is directed in the commanded direction with the commanded deflection efficiency. A driver that applies an AC voltage to the acoustooptic element so as to be deflected; and a storage area that stores a physical quantity that determines deflection efficiency in association with each of a plurality of emission directions; And a control device that commands the emission direction from the control unit, and when the driver is instructed by the control device a physical quantity that determines the emission direction and the deflection efficiency, And a beam distribution device for applying an AC voltage to the acoustooptic device at a frequency and an amplitude such that the deflection efficiency is the deflection efficiency associated with the emission direction stored in the storage area. Provided.

  Furthermore, according to another aspect of the present invention, by changing the deflection angle of the incident laser beam, one path is selected from a plurality of paths, and the laser beam is emitted along the selected path. A beam distribution device that can set the deflection efficiency for each deflection angle, a stage that holds the object to be irradiated, and a plurality of paths on the emission side of the beam distribution device are arranged corresponding to each of the corresponding paths. An irradiation optical system that makes a laser beam propagating along the irradiation object incident on an object to be irradiated held on the stage, and the beam distribution device has a relatively large attenuation amount of the laser beam when passing therethrough. When a laser beam is emitted along a path corresponding to the optical system, a multi-axis laser irradiation device that relatively increases the deflection efficiency is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the beam distribution apparatus which can control deflection | deviation efficiency can be provided in the case of beam distribution.

  In addition, it is possible to provide a multi-axis laser irradiation apparatus capable of controlling the deflection efficiency in beam distribution.

  FIG. 1 is a schematic view showing a laser processing apparatus according to the first embodiment.

  The laser processing apparatus according to the first embodiment includes a laser light source 20, an acoustooptic deflector (AOD) 22, a deflection angle expander 23, a beam damper 24, reflecting mirrors 25a to 25h, galvano scanners 26a to 26d, and fθ lenses 27a to 27d. The shaft moving mechanisms 28 and 29 and the control device 30 are included.

  In response to a trigger signal transmitted from the control device 30, a pulse laser beam Lb is emitted from the laser light source 20, for example, a carbon dioxide laser. The pulse laser beam Lb is incident on an acousto-optic deflector (AOD) 22.

  As shown in the figure, an incident laser beam Lb can be distributed to, for example, five optical axes using an acousto-optic deflector (AOD) 22. The laser beam Lb is emitted along the optical axis I as it is when no electrical signal (high frequency voltage) RF is applied to the acoustooptic deflector (AOD) 22. When an electrical signal RF having a frequency (referred to as frequency fa) is applied to the acousto-optic deflector (AOD) 22, a laser beam Lba that is diffracted at a certain diffraction angle and propagates along the optical axis Ia is generated. Emitted. Similarly, when electrical signals RF having frequencies fb, fc, and fd different from fa are applied to the acousto-optic deflector (AOD) 22, laser beams Lbb that propagate along the optical axes Ib, Ic, and Id, respectively. Lbc and Lbd are emitted.

  The angle formed by the optical axes Ia and Ib, the angle formed by the optical axes Ib and Ic, and the angle formed by the optical axes Ic and Id are all 0.66 °, for example.

  The electrical signal RF is applied based on a control signal from the control device 30.

  The pulse laser beam emitted from the acousto-optic deflector (AOD) 22 is incident on the deflection angle expander 23. The deflection angle expander 23 is emitted adjacent to each other when the beams are emitted along the optical axes Ia to Id, rather than the angle formed by the adjacent incident beams (the angle between the adjacent incident beams). The laser beam is emitted in such a manner that the angle formed by the beams to be emitted (the angle between adjacent emitted beams) is increased. The deflection angle expander 23 will be described in detail with reference to the next figure.

  When the electrical signal RF is not applied to the acousto-optic deflector (AOD) 22, the laser beam incident on the deflection angle expander 23 along the optical axis I enters the beam damper 24. In this figure, an example is shown in which the light is incident on the beam damper 24 via the deflection angle expander 23, but may be incident on the beam damper 24 without passing through the deflection angle expander 23.

  The laser beam emitted from the deflection angle expander 23 travels along any one of the optical axes Iaa to Idd, and passes through the reflecting mirrors 25a to 25d, the galvano scanners 26a to 26d, and the fθ lenses 27a to 27d, respectively. It enters the printed circuit board 33 or 34 that is the object to be processed.

  The printed boards 33 and 34 are fixed on the XY stage 31 by a chuck plate 32. A laser beam traveling along optical axes Iaa and Ibb is incident on the printed circuit board 33, and a laser beam traveling along optical axes Icc and Idd is incident on the printed circuit board 34. The XY stage 31 can move the printed boards 33 and 34 in a plane parallel to the board.

  By the operation of the galvano scanner 26a and the XY stage 31, the galvano scanner 26a, the fθ lens 27a, and the XY stage 31 so that the laser beam traveling along the optical axis Iaa can be incident on all the processing positions of the printed circuit board 33. , And a printed circuit board 33 are arranged.

  Similarly, by the operation of the galvano scanner 26c and the XY stage 31, the galvano scanner 26c, the fθ lens 27c, so that the laser beam traveling along the optical axis Icc can be incident on all processing positions of the printed circuit board 34. An XY stage 31 and a printed circuit board 34 are arranged.

  The laser beam traveling along the optical path Ibb is reflected by the three reflecting mirrors 25b, 25e, and 25f, scanned by the galvano scanner 26b, condensed by the fθ lens 27b, and incident on the printed circuit board 33. The axis moving mechanism 28 moves the reflecting mirror 25f, the galvano scanner 26b, and the fθ lens 27b, for example, in the in-plane direction of the printed circuit board 33 (substrate mounting surface of the XY stage) based on a control signal from the control device 30. Can do.

  The laser beam traveling along the optical path Idd is reflected by the three reflecting mirrors 25d, 25g, and 25h, then scanned by the galvano scanner 26d, condensed by the fθ lens 27d, and incident on the printed circuit board 34. To do. The axis moving mechanism 29 moves the reflecting mirror 25h, the galvano scanner 26d, and the fθ lens 27d, for example, in the in-plane direction of the printed circuit board 34 (substrate mounting surface of the XY stage) based on a control signal from the control device 30. Can do.

  The laser processing apparatus shown in this figure is a two-panel four-axis laser processing apparatus having two processing axes per panel. Since one axis per panel can be moved in the in-plane direction of the printed circuit boards 33 and 34 by the axis moving mechanisms 28 and 29, 2 is selected so as to be optimal for processing according to the panel size and wiring pattern. The distance between the axes can be adjusted.

  In the laser processing apparatus according to the first embodiment, the beam energy of an attenuator or the like is on the optical path of the laser beam after being emitted from the acousto-optic deflector (AOD) 22 and entering the processing objects 33 and 34. The adjusting device is not arranged. This will be described later with reference to FIG.

  FIG. 2 is a schematic diagram showing an example of the deflection angle expander 23.

  The deflection angle expander 23 includes a parallel mirror 40 composed of two reflecting mirrors provided with light extraction windows 41a to 41d, for example. The two reflecting mirrors are arranged so that the mirror surfaces face each other. The optical paths of the laser beams Lba to Lbd that are deflected at different angles by the acousto-optic deflector (AOD) 22 and enter the deflection angle expander 23 will be described with reference to FIG. It is assumed that the deflection angle given by the acousto-optic deflector (AOD) 22 is the smallest Lba and increases in the order of Lbb, Lbc, and Lbd.

  The laser beams Lba to Lbd deflected by the acousto-optic deflector (AOD) 22 are guided between the two reflecting mirrors through the light introduction window 42, are repeatedly reflected between them, and are in the vicinity of the light extraction windows 41a to 41d. It progresses to.

  The light extraction windows 41a and 41b are formed in one reflecting mirror, and the light extraction windows 41c and 41d are formed in the other reflecting mirror.

  Laser beams Lba, Lbb, Lbc, and Lbd are emitted from the light extraction windows 41a, 41c, 41b, and 41d, respectively. The light extraction windows 41a to 41d also serve as a mask for limiting the light transmission region. When there are overlapping portions due to the spread of the laser beams Lba to Lbd, the overlapping portions are cut. In addition, the non-reflective coating is given to the circumference | surroundings of the light extraction windows 41a-d so that the cut overlap part may not be reflected.

  The laser beams Lba, Lbb, Lbc, and Lbd are respectively guided to the optical paths Iaa, Icc, Ibb, and Idd shown in FIG. 1 using a reflecting mirror outside the parallel mirror 40, for example. The reflecting mirror outside the parallel mirror 40 is disposed, for example, on the upper side in the figure, and reflects the laser beams Lbb and Lbd on the lower side in the figure.

  Laser beams Lba and Lbc emitted from the acousto-optic deflector (AOD) 22 with a deflection angle difference of 1.32 °, for example, are emitted from the deflection angle expander 23 so as to be emitted from the deflection angle expander 23. The angle between adjacent beams can be, for example, 1.32 °. The angle between the emission directions of the laser beam Lbc and the laser beams Lbb and Lbd is arbitrarily set to, for example, 1.32 ° and 2.64 °, depending on the arrangement angle of the external reflecting mirror arranged on the upper side of the drawing. Can be adjusted.

  The laser processing apparatus according to the first embodiment is a two-panel four-axis laser processing apparatus using an acousto-optic deflector (AOD).

  FIG. 3 is a schematic view showing another example of the deflection angle expander 23.

  The deflection angle expander 23 can be configured by using two convex lenses having different focal lengths.

The first convex lens 61 having a focal length f ₁ is disposed on the beam incident side, and the second convex lens 62 having a focal length f ₂ is disposed on the beam exit side. The focal lengths of the two convex lenses 61 and 62 satisfy the relationship of f ₁ > f ₂ . The first and second convex lenses 61 and 62 are optically aligned.

Laser beams Lba and Lbb emitted from an acousto-optic deflector (AOD) with a deflection angle difference θ ₁ , for example, 0.66 °, pass through the first convex lens 61 and the second convex lens 62 in this order. The beam diameter of the laser beam Lba at the time of incidence and the beam diameter of the laser beam Lba at the time of emission are D ₁ and D ₂ , respectively, and the angles formed by the emission directions of the laser beams Lba and Lbb when the second convex lens 62 is emitted If θ ₂ is satisfied, the following equation (1) is established.

θ ₂ / θ ₁ = f ₁ / f ₂ = D ₁ / D ₂ (1)
From f ₁ > f ₂ , θ ₂ > θ ₁ is satisfied. It can be seen that the laser beams Lba and Lbb incident on the deflection angle expander 23 are emitted at an angle difference θ ₂ larger than the angle θ ₁ formed by the traveling direction at the time of incidence.

  The laser processing method according to the embodiment will be described with reference to FIGS.

  FIG. 4A is a schematic cross-sectional view showing a part of the printed circuit boards 33 and 34 that are objects to be processed.

  The printed boards 33 and 34 have a structure in which an epoxy resin layer (insulating layer) 51 is formed on a copper layer 52 and a copper layer (metal layer) 50 is formed on the epoxy resin layer 51. In the laser processing method according to the embodiment, first, a one-shot pulse laser beam is incident on the printed circuit boards 33 and 34 from the surface of the blackened copper layer 50 to penetrate the copper layer 50 and the epoxy resin layer 51. A hole that exposes the bottom surface is formed. Subsequently, a one-shot or multiple-shot pulsed laser beam is incident on the epoxy resin layer 51 through a hole penetrating the copper layer 50 to form a hole that penetrates the epoxy resin layer 51 and exposes the copper layer 50 on the bottom surface. To do.

  With reference to FIG. 4 (B), the drilling process of the epoxy resin layer 51 is demonstrated.

  Drilling of the epoxy resin layer 51 is performed by forming a hole penetrating the copper layer 52 by a pulse laser beam incident along the four optical paths Iaa to Idd shown in FIG. Is performed by irradiating a pulse laser beam.

  The pulse laser beam incident on the epoxy resin layer 51 is obtained, for example, by dividing one shot pulse laser beam emitted from a laser light source into four along the time axis. For example, as shown in FIG. 4 (B), a high frequency voltage is applied to the acousto-optic deflector (AOD) to change the frequency except for the rise and fall times where the energy stability is poor, and one shot is divided into four. Then, the divided four laser pulses are respectively introduced into the optical paths Iaa to Idd.

  Rather than using a four-shot pulse laser beam emitted from a laser light source, the one-shot beam is divided into four parts and incident on the epoxy resin layer 51 to perform drilling, so the processing time of the epoxy resin layer 51 is shortened. can do.

  With reference to FIG.4 (C)-(E), the drilling process of the copper layer 50 is demonstrated.

  Reference is made to FIG.

  Similar to the processing of the epoxy resin layer 51, in the processing of the copper layer 50, one shot pulse laser beam emitted from the laser light source is divided into four along the time axis by an acousto-optic deflector (AOD), and the optical path It is considered that the distribution may be made to Iaa to Idd. However, since copper has poor processability as compared with an epoxy resin, more energy is required when making a hole in the copper layer 50 than when making a hole in the epoxy resin layer 51.

  Therefore, as shown in FIG. 4C, a method is conceivable in which the pulse width is increased and the energy necessary for drilling the copper layer 50 is secured under the condition that the repetition frequency is constant.

  FIG. 4D is a graph schematically showing the relationship between the duty and the pulse energy under the condition that the repetition frequency is constant.

  As can be seen from this graph, when a certain duty range is exceeded, the pulse energy decreases as the duty increases. Therefore, as described above, even if the pulse width is increased in order to ensure the energy necessary for drilling the copper layer 50, sufficient processing energy may not be obtained.

  Reference is made to FIG.

  For this reason, in the laser processing method according to the embodiment, the one-shot pulse laser beam is divided into two along the time axis, and the copper layer 50 is processed. For example, for the first shot, an acousto-optic deflector (AOD) is used to deflect the laser pulse divided in two in a predetermined direction, and from the surface of the copper layer 50 to the printed circuit boards 33 and 34 along the optical paths Iaa and Icc. Incidently, a hole penetrating the copper layer 50 at the incident position is opened. For the second shot, an acousto-optic deflector (AOD) is used to cause a laser pulse divided in two to enter the printed circuit boards 33 and 34 from the surface of the copper layer 50 along the optical paths Ibb and Idd. A hole penetrating the copper layer 50 is made.

  The third shot is divided into four. By applying high-frequency voltages of different frequencies to the acousto-optic deflector (AOD), the divided laser pulses travel in the optical paths Iaa to Idd. The laser pulse enters the epoxy resin layer 51 through the holes formed in the copper layer 50 of the printed boards 33 and 34, penetrates the epoxy resin layer 51, and forms a hole exposing the copper layer 52 on the bottom surface.

  Since the number of divisions of the pulse laser beam is made different between the processing of the copper layer 50 and the processing of the epoxy resin layer 51 and the beam of appropriate energy is irradiated, the processing can be performed with good processing quality.

  FIG. 5 is a schematic view showing a laser processing apparatus according to the second embodiment.

  The laser processing apparatus according to the second embodiment includes a laser light source 20, an acousto-optic deflector (AOD) 22, cylindrical lenses 65 and 66a to 66d, a mask 69 having a light transmitting region (slit), reflecting mirrors 25a to 25d, and a galvano. The scanner 26a-26d, the f (theta) lens 27a-27d, and the control apparatus 30 are comprised.

  A pulsed laser beam Lb is emitted from the laser light source 20. The pulse laser beam Lb is incident on an acousto-optic deflector (AOD) 22. The acousto-optic deflector (AOD) 22 gives different deflection angles to the incident laser beam Lb according to the frequency of the high-frequency voltage RF applied by the control device 30, for example, is divided into four along the time axis. In the in-plane direction, the light is emitted in four different directions.

  The four laser beams Lba to Lbd emitted from the acoustooptic deflector (AOD) 22 enter, for example, a cylindrical lens 65 whose length direction is arranged parallel to the vertical direction of the drawing, and become narrow in the drawing plane. Thus, the light is condensed and is incident on different slits of the mask 69 arranged at the condensing position. The four laser beams Lba to Lbd are separated from each other by passing through different slits of the mask 69.

  The reflecting mirrors 25a to 25d are arranged immediately after the mask 69, and reflect the laser beams Lba to Lbd in different directions, respectively. The cylindrical lenses 66a to 66d are disposed on the optical paths of the laser beams Lba to Lbd reflected by the reflecting mirrors 25a to 25d, respectively. The laser beams Lba to Lbd incident on the cylindrical lenses 66a to 66d are emitted as parallel light having a circular cross section, for example.

  The laser beams Lba to Lbd emitted from the cylindrical lenses 66a to 66d are reflected by the folding mirror, and irradiated to the printed circuit boards 33 and 34 through the galvano scanners 26a to 26d and the fθ lenses 27a to 27d, respectively. The printed boards 33 and 34 are fixed on the XY stage 31 by a chuck plate 32.

  Similarly to the laser processing apparatus according to the first embodiment, the laser processing apparatus according to the second embodiment divides the laser beam incident on the acousto-optic deflector (AOD) along the time axis and emits it at different deflection angles. By doing so, different positions of the object to be processed can be processed almost simultaneously.

  Even when a laser beam is emitted in, for example, four different directions by an acousto-optic deflector (AOD), each beam can be separated and irradiated onto a workpiece.

  In the laser processing apparatus according to the second embodiment, the acoustooptic deflector (AOD) 22 and the cylindrical lens 65 are arranged so that the laser beam deflected by the acoustooptic deflector (AOD) 22 enters the cylindrical lens 65. However, both may be arranged so that the laser beam transmitted through the cylindrical lens 65 enters the acousto-optic deflector (AOD) 22.

  In the laser processing apparatus according to the second embodiment shown in FIG. 5, it is not preferable to use a convex lens instead of the cylindrical lens 65. Since the laser beam is focused on a small spot, for example, when a reflection mirror or a galvano scanner is arranged between the convex lens and the object to be processed, the mirror arranged in the middle may be damaged.

  Similar to the first embodiment, in the laser processing apparatus according to the second embodiment, the laser beam emitted from the acousto-optic deflector (AOD) 22 until it enters the workpieces 33 and 34 is also shown. A beam energy adjusting device such as an attenuator is not arranged on the optical path. This will be described later with reference to FIG.

  FIG. 6 is a schematic view showing a laser processing apparatus according to the third embodiment.

  The laser processing apparatus according to the third embodiment includes a laser light source 20, a convex lens 67, an acousto-optic deflector (AOD) 22, a concave lens 68, and a control device 30.

A pulsed laser beam Lb is emitted from the laser light source 20. The pulse laser beam Lb travels while spreading at a certain spread angle and enters the convex lens 67. The convex lens 67 converges and emits the pulse laser beam Lb. The pulse laser beam Lb travels while converging, and enters the acousto-optic deflector (AOD) 22. The acousto-optic deflector (AOD) 22 gives different deflection angles to the incident laser beam Lb according to the frequency of the high-frequency voltage RF applied by the control device 30, for example, is divided into four along the time axis and is different. It emits in 4 directions. The angle formed by the emission directions of the laser beams emitted adjacent to each other is constant. The angle and theta _3.

The laser beam emitted from the acousto-optic deflector (AOD) 22 enters the concave lens 68. The concave lens 68 has an angle (θ ₄ ) formed between the emission directions of adjacent laser beams (center rays) (θ ₄ ) and an angle (θ) formed between the adjacent incident laser beams (center rays). ₃ ) (θ ₄ > θ ₃ ) and emit laser beams Lba to Lbd. The laser beams Lba to Lbd are all parallel beams, for example.

  As the optical system after the concave lens 68 in FIG. 6, for example, an optical system including the reflecting mirrors 25a to 25d, the galvano scanners 26a to 26d, and the fθ lenses 27 to d in FIG.

  The laser beam machining apparatus according to the third embodiment is also different from the laser beam machining apparatus according to the first and second embodiments by dividing the laser beam incident on the acousto-optic deflector (AOD) along the time axis. By emitting at a deflection angle, different positions of the workpiece can be processed almost simultaneously. For example, even when laser beams are emitted in four different directions by an acousto-optic deflector (AOD), each beam can be separated and irradiated onto a workpiece.

  The convex lens 67 desirably has a relatively long focal length, for example, a focal length of several tens of centimeters or more, and makes the laser beam incident on the acousto-optic deflector (AOD) close to parallel light, for example. When the focal length is short, when the laser beam passes through the acousto-optic deflector (AOD), the beam size is reduced, the light density is increased, and the acousto-optic deflector (AOD) is damaged. is there. In addition, when the focal length is short, a beam having a high degree of convergence is incident on the acousto-optic deflector (AOD), which may reduce the diffraction efficiency.

  Furthermore, the beam after passing through the concave lens 68 does not necessarily have to be a parallel beam. For example, the optical system can be formed so that the beam converges gently.

  In the laser processing apparatus according to the third embodiment, a combination of a convex lens and a concave lens is used as a combination of an optical member for converging the beam and an optical member for diverging the beam (increasing the separation angle). It is also possible to use a combination of a cylindrical lens and a concave cylindrical lens, or a combination of a concave mirror and a convex mirror. A convex lens and a convex mirror, or a concave mirror and a concave lens may be combined.

  When a combination of a convex cylindrical lens and a concave cylindrical lens is used, for example, two cylindrical lenses are arranged so that the length directions of both cylindrical lenses are parallel to the direction perpendicular to the paper surface of FIG. In this arrangement, the laser beam incident on the convex cylindrical lens is emitted while converging in the plane of the paper of FIG. 6, and the laser beam incident on the concave cylindrical lens is adjacent in the plane of the paper of FIG. The light is emitted so that the angle between the central rays that are emitted is larger than the angle between the central rays that are adjacent to each other.

  As in the first and second embodiments, in the laser processing apparatus according to the third embodiment, the laser beam is emitted from the acousto-optic deflector (AOD) 22 and then enters the workpieces 33 and 34. A beam energy adjusting device such as an attenuator is not arranged on the optical path of the laser beam.

  With reference to FIG. 7, the control apparatus 30 which controls the acousto-optic deflector (AOD) 22 is explained in full detail.

  The control device 30 includes a driver 30a and a control circuit 30b. In relation to the driver 30a, the control circuit 30b gives a port selection signal to at least the driver 30a. The port selection signal is a signal that indicates which of the optical axes Ia to Id emits the laser beam Lb incident on the acousto-optic deflector (AOD) 22.

  The driver 30a applies a high-frequency electrical signal RF to the acousto-optic deflector (AOD) 22 based on the given port selection signal.

  As described above, the deflection angles (the optical paths Ia to Id of the laser beam emitted from the acoustooptic deflector (AOD) 22) that the acoustooptic deflector (AOD) 22 gives to the incident laser beam Lb depending on the frequency of the electrical signal RF. Determined. The intensity of the laser beam emitted from the acousto-optic deflector (AOD) 22 is determined by the intensity of the laser beam incident on the acousto-optic deflector (AOD) 22 and the amplitude of the electric signal RF. The intensity of the laser beam emitted from the acousto-optic deflector (AOD) 22 increases as the amplitude of the electrical signal RF increases.

  Ratio of the intensity of the laser beam emitted from the acousto-optic deflector (AOD) 22 and the intensity of the laser beam incident on the acousto-optic deflector (AOD) 22 ((the laser beam emitted from the acousto-optic deflector (AOD) 22) (Intensity) / (Intensity of laser beam incident on acousto-optic deflector (AOD) 22)) is referred to as deflection efficiency. Even when a laser beam of constant intensity is incident on an acousto-optic deflector (AOD) 22 and an electric signal RF having the same amplitude is applied to the acousto-optic deflector (AOD) 22, a deflection angle applied to the laser beam. The deflection efficiency varies depending on (the frequency of the electric signal RF). If the frequency of the electrical signal RF is the same, the deflection efficiency depends on the amplitude of the electrical signal RF.

  The driver 30a of the control device 30 included in each embodiment corresponds to each port (the emission direction and deflection angle of the beam emitted from the acousto-optic deflector (AOD) 22) according to the port selection signal given from the control circuit 30b. The electrical signal RF is transmitted to the acousto-optic deflector (AOD) 22 in accordance with the deflection efficiency determined in advance and stored in the memory in the driver 30a. The frequency of the electrical signal RF to be transmitted is determined by the selected port. The amplitude of the electric signal RF is determined independently for each selected port, and is determined by the stored predetermined deflection efficiency.

  For example, in the laser processing apparatus shown in FIG. 1, the deflection efficiency is such that the beam intensity on the processing surface is appropriate for processing when the laser beam traveling on the optical paths Iaa to Idd is irradiated onto the printed circuit boards 33 and 34. It is determined in advance so as to be the same for each optical path.

  In the case shown in FIG. 1, the amount of attenuation of the laser beam is relatively large due to the presence of many optical members after exiting the deflection angle expander 23 and entering the printed circuit boards 33 and 34, so the optical path Ibb. And relatively high deflection efficiency is set in advance for the ports corresponding to Idd.

  In the laser processing apparatus according to the embodiment, for example, the deflection efficiency is determined so that the beam intensity is the same at each processing position and suitable for processing. Therefore, the laser beam emitted from the acousto-optic deflector (AOD) 22 is emitted. There is no need to arrange a beam energy adjusting device such as an attenuator on the optical path. For this reason, the component of an apparatus can be decreased.

  Instead of storing the deflection efficiency in the memory in the driver 30a, for example, the amplitude itself may be stored as a physical quantity for determining the deflection efficiency. Further, a memory in which a physical quantity for determining the deflection efficiency is stored not in the driver 30a but in the control circuit 30b, and the deflection efficiency at the selected port is given from the control circuit 30b to the driver 30a together with the port selection signal. Can also be adopted.

  As mentioned above, although this invention was demonstrated along the Example, this invention is not limited to these. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  The beam distribution device can be used for various devices having a structure for distributing beams.

  The multi-axis laser irradiation apparatus can be used for general laser processing, for example, laser drilling.

It is the schematic which shows the laser processing apparatus by a 1st Example. 3 is a schematic diagram illustrating an example of a deflection angle expander 23. FIG. 6 is a schematic diagram showing another example of the deflection angle expander 23. FIG. (A)-(E) is a figure for demonstrating the laser processing method by an Example. It is the schematic which shows the laser processing apparatus by a 2nd Example. It is the schematic which shows the laser processing apparatus by a 3rd Example. It is a figure for explaining in detail the control apparatus 30 which controls the acousto-optic deflector (AOD) 22. (A) And (B) is the schematic which shows the laser beam radiate | emitted from the acousto-optic deflector (AOD) 10.

Explanation of symbols

10 Acousto-optic deflector (AOD)
20 Laser light source 21 Convex lens 22 Acousto-optic deflector (AOD)
23 Deflection angle expander 24 Beam dampers 25a to h Reflective mirrors 26a to d Galvano scanners 27a to d fθ lenses 28, 29 Axis moving mechanism 30 Controller 30a Driver 30b Control circuit 31 XY stage 32 Chuck plates 33, 34 Printed circuit board 40 Parallel mirror 41a-d Light extraction window 42 Light introduction window 50, 52 Copper layer 51 Epoxy resin layer 61 First convex lens 62 Second convex lens 65 Cylindrical lens 67 Convex lens 68 Concave lens

Claims (3)

An AC voltage is applied to change the traveling direction of the incident laser beam, the deflection angle depends on the frequency of the applied AC voltage, and the deflection efficiency depends on the amplitude of the applied AC voltage. An optical element;
A driver that applies an AC voltage to the acoustooptic device to deflect the laser beam in the commanded direction by commanding the emission direction;
A control device for instructing the direction of emission from the acoustooptic device to the driver;
The driver includes a storage area that stores a physical quantity that determines deflection efficiency in association with each of a plurality of emission directions, and when the emission direction is commanded from the control device, the emission direction is set to the commanded direction. And a beam distribution device that determines the frequency and amplitude so that the deflection efficiency is the deflection efficiency associated with the emission direction stored in the storage area, and applies an AC voltage to the acoustooptic device . An AC voltage is applied to change the traveling direction of the incident laser beam, the deflection angle depends on the frequency of the applied AC voltage, and the deflection efficiency depends on the amplitude of the applied AC voltage. An optical element;
A driver that applies an AC voltage to the acoustooptic device so as to deflect the laser beam in the commanded direction with the commanded deflection efficiency by commanding a physical quantity that determines the emission direction and the deflection efficiency; ,
A storage area that stores a physical quantity that determines deflection efficiency in association with each of a plurality of emission directions, and has a control device that commands the emission direction from the acousto-optic element to the driver;
When a physical quantity for determining the emission direction and the deflection efficiency is commanded from the control device, the driver is set to the commanded direction, and the deflection efficiency is stored in the storage area. A beam distribution device that applies an AC voltage to the acoustooptic device at a frequency and amplitude such that a deflection efficiency associated with an emission direction is obtained. By changing the deflection angle of the incident laser beam, it is possible to select one path from a plurality of paths, emit the laser beam along the selected path, and set the deflection efficiency for each deflection angle. A beam distribution device;
A stage for holding the irradiated object;
An irradiation optical system that is arranged corresponding to each of a plurality of paths on the emission side of the beam distribution device and that makes a laser beam propagating along the corresponding path incident on an object to be irradiated held on the stage. And
The beam distribution device is configured to irradiate a multi-axis laser beam having a relatively large deflection efficiency when the laser beam is emitted along a path corresponding to the irradiation optical system in which the attenuation amount of the laser beam when passing is relatively large. apparatus.

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