JP2009125777A - Laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus that facilitates maintenance inspection and improves machining efficiency. <P>SOLUTION: The optical path of a laser beam 2 outputted from a laser oscillator 1 is made switchable to a first and a second directions by an optical path converter 4. In the second direction, the laser beam is split into a first space division beam 5a and a second space division beam 5b each having a different optical path by a beam splitter 9, with each supplied to irradiation heads 100, 101 respectively. Also, with two optical path deflectors 6a, 6b arranged in the first direction, either a first time division beam 7a or a second time division beam 7b can be outputted each having a different optical path. Then, an arrangement is made so that the optical axis of the time division beam 7a passing through a polarizing beam splitter 26 becomes co-axial with the optical axis of the space division beam 5a, and that the optical axis of the time division beam 7b passing through a polarizing beam splitter 27 becomes co-axial with the optical axis of the space division beam 5b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus that performs processing or cutting of holes using laser light.

  Along with the downsizing and high-density mounting of electronic devices, printed wiring boards are mainly multilayer wiring boards in which a plurality of boards are stacked. In a multilayer wiring board, it is necessary to electrically connect conductive layers between substrates stacked one above the other. Therefore, via holes (holes) reaching the lower conductive layer are formed in the insulating layer of the multilayer wiring board, and conductive plating is applied to the inside of the via holes, so that the conductive layers between the stacked substrates are electrically connected. is doing.

The formation of the via hole, with the miniaturization of the via hole, UV lasers using C0 ₂ laser and YAG harmonic high output is used. Further, by using a beam scanning optical system in which a galvanometer mirror and an fθ lens are combined, high-speed processing is realized by scanning a laser beam. Further, an imaging optical system is employed in which a circular aperture is used as a mask to select a hole diameter to be processed, and the image is transferred onto a substrate using an fθ lens. In addition, the shape quality of the via hole is improved by irradiating one via hole with laser light in a plurality of times.

  However, the demand for improved throughput for drilling in printed circuit board manufacturing has become increasingly severe as the number of holes has increased due to higher density. In addition, as the hole diameter is reduced, the requirements for positional accuracy are becoming stricter as well.

  In order to meet the above requirements, a plurality of laser processing apparatuses having multiple processing beams have been proposed. As a method of multi-sizing, for example, a laser processing device that spatially divides the energy of laser light by using a half mirror to make a multi-beam, and a laser processing device that changes laser light temporally to make a multi-beam Is.

  However, when the energy of the laser beam is spatially divided into multi-beams, in order to obtain two split beams having a peak value of WP per head necessary for processing, the capacity of the peak value of 2 WP It is necessary to prepare a large laser oscillator. Further, when the laser beam is divided by the half mirror, the transmitted beam and the reflected beam are generated at the same time. Therefore, the number of processed portions in the two scan regions must be the same, and the types of printed circuit boards that can be processed are limited. Also, it is difficult to make the number of heads odd.

  On the other hand, in a laser processing apparatus that changes the laser light in time to form a multi-beam, for example, when two heads process the same workpiece, compared to a laser processing machine that spatially divides the energy of the laser light. Machining speed becomes slow.

  Therefore, the incident laser is branched and emitted to a first branch laser that is coaxial with the optical axis of the laser on which the optical axis is incident, and a second branch laser that intersects the optical axis of the laser on which the optical axis is incident. A beam splitter and a beam splitter which is configured to be able to be inserted into and extracted from the optical axis of the laser output from the laser oscillator between the laser oscillator and the optical path deflector and which is positioned on the optical axis of the laser And a third optical system for guiding the second branch laser branched from the laser beam to the laser irradiation unit to which the first branch laser is not supplied, and the laser is either one or both of the two laser irradiation units There is a laser processing apparatus that can be selected to supply to (Patent Document 1).

  According to the technique of Patent Document 1, the laser oscillator can be used effectively and various workpieces can be processed.

JP 2006-281268 A

  However, the laser processing apparatus of Patent Document 1 requires a moving device for moving the beam splitter and the mirror between the operating position and the standby position according to the processing content, and the apparatus becomes a large scale, The beam splitter and mirror could be misaligned. For this reason, regular maintenance inspections were required. Further, when processing one hole with pulses having different peak intensities, it takes time to move the beam splitter and the mirror, and the work efficiency is lowered.

  An object of the present invention is to provide a laser processing apparatus that solves the above-described problems, can be easily maintained and inspected, and can improve processing efficiency.

In order to solve the above-described problems, the laser processing apparatus of the present invention converts the laser (2) output from the laser oscillator (1) into a time division beam (7a, 7b) and a space division beam (5a, 5b), respectively. In the laser processing apparatus divided and supplied to one of the first and second laser irradiation units (100, 101),
Sequentially arranged on the optical axis of the laser (2) output from the laser oscillator (1), the incident laser from the laser oscillator is deflected at a predetermined angle with respect to the first direction or the first direction. A first optical path deflector (4) that emits in the second direction, and a laser beam from the incident first optical path deflector (4) is given in a predetermined direction with respect to the first direction or the first direction. A second optical path deflector (6a) that emits in an angularly deflected third direction and a laser in the first direction from the incident second optical path deflector (6a) as the second laser irradiation unit An optical device (6b) directed in a fourth direction to (101);
The laser beam emitted from the first optical path deflector (4) in the second direction is divided and guided to the first laser irradiation unit (100) as a first space-divided beam (5a). First and second optical systems (28, 9, 10, 26, and 28, 9, 11, 27) that lead to the second laser irradiation unit (101) as two spatially divided beams (5b);
A third optical system for guiding the laser beam emitted from the second optical path deflector (6a) in the third direction to the first laser irradiation section (100) as a first time-division beam (7a) ( 12, 13, 14),
A fourth optical system (15, 16) for guiding the laser emitted from the optical unit (6b) in the fourth direction to the second laser irradiation unit (101) as a second time-division beam (7b). When,
It is possible to select to supply the laser to one or both of the two laser irradiation units (100, 101).

  The optical device emits the incident laser beam from the second optical path deflector (6a) in the first direction or the fourth direction deflected by a predetermined angle with respect to the first direction. A third optical path deflector (6b) is preferred.

  Furthermore, the first and second optical systems are arranged on the optical path of the laser emitted in the second direction, and change the polarization direction of the incident laser, and the half-wave plate (28), It is preferable to include a first beam splitter (9) that spatially divides the laser that has passed through the half-wave plate.

  In addition, the first optical system is configured such that the optical axis of the first space-divided beam (5a) and the optical axis of the first time-divided beam (7a) coincide with each other, and the first laser irradiation unit ( 100), and the second optical system includes an optical axis of the second space division beam (5b) and the second time division beam (7b). It is preferable to include a second polarization beam splitter (27) that is incident on the second laser irradiation unit (101) so as to coincide with the optical axis.

  Note that the reference numerals in the parentheses are for comparison with the drawings, but this is for convenience to facilitate understanding of the invention and has no influence on the description of the claims. It is not a thing.

  According to the present invention, the optical path of the laser is deflected by switching on / off the first and second optical path deflectors, instead of performing laser processing by mechanically moving the beam splitter and mirror as in the prior art. However, since the laser processing is performed, it is not necessary to periodically inspect the beam splitter and the mirror for positional deviation, and the maintenance inspection becomes easy. Furthermore, since it does not take time to move the beam splitter and the mirror as in the prior art, rapid laser processing can be performed, and the processing efficiency can be improved.

  Embodiments according to the present invention will be described below. FIG. 1 is a configuration diagram of a laser processing apparatus according to the present invention.

  First, the configuration of the first and second irradiation heads will be described.

  In FIG. 1, a first irradiation head (first laser irradiation unit) 100 includes a first biaxial scanner 18 and an fθ lens 20, and a second irradiation head (second laser irradiation unit) 101. Consists of a second biaxial scanner 19 and an fθ lens 21. The first two-axis scanner 18 includes a galvano scanner 18b to which a mirror 18a for swinging in the X-axis direction with respect to the processing area of the substrate 24 on the XY stage 22 and a mirror 18c for swinging in the Y-axis direction. And a galvano scanner 18d to which is attached. The second biaxial scanner 19 includes a galvano scanner 19b to which a mirror 19a for oscillating in the X axis direction with respect to the processing area of the substrate 25 on the XY stage 22 and a galvano scanner 19b for oscillating in the Y axis direction. And a galvano scanner 19d to which a mirror 19c is attached. The processing area by the first biaxial scanner 18 and the second biaxial scanner 19 is about 50 × 50 mm square.

  Next, the optical path of laser light will be described.

  That is, this laser processing apparatus is sequentially arranged on the optical axis of the laser beam 2 output from the laser oscillator 1, and the incident laser beam 2 from the laser oscillator 1 is directed to the first direction or the first direction. The optical path switch (first optical path deflector) 4 that emits in a second direction deflected by a predetermined angle and the laser light 2 from the incident optical path switch 4 with respect to the first direction or the first direction The beam distribution shaper (second optical path deflector) 6a that emits in a third direction deflected by a predetermined angle and the laser beam 2 in the first direction from the incident beam distribution shaper 6a in the first direction Or a beam distribution / shaping device (optical device, third optical path deflector) 6b that emits in a fourth direction deflected by a predetermined angle with respect to the first direction. To supply either or both of 101 And is configured so that it can be-option.

  The P-polarized laser light 2 is emitted from the laser oscillator 1 in response to a command from a host controller (not shown) of the laser processing machine, and enters the optical path switch 4 through the mask 3. The optical path switch 4 is composed of an acousto-optic device, and shapes the function of deflecting the direction of the laser beam 2 in the ON state and the pulse waveform into a rectangular shape in response to a command from a host control device (not shown) of the laser processing machine. With functionality.

  When the optical path switch 4 is ON, the laser beam 2 is incident on the half-wave plate 28 while changing the traveling direction. The laser light 2 transmitted through the half-wave plate 28 enters the beam splitter 9 as S-polarized laser light 2, 50% is reflected, and the remaining 50% is transmitted to the first space split beam 5 a. Thus, the second space split beam 5b is obtained. The first space-divided beam 5a is reflected by the fixed mirror 10 and the first polarization beam splitter 26, and is incident on the fθ lens 20 by the first biaxial scanner 18 so as to be installed on the XY stage 22. Irradiate a predetermined position of the substrate 24. The second space split beam 5 b is reflected by the fixed mirror 11 and the second polarization beam splitter 27, and the incident angle to the fθ lens 21 is controlled by the second biaxial scanner 19, so that it is placed on the XY stage 22. Irradiate a predetermined position of the installed substrate 25. The polarization beam splitters 26 and 27 have characteristics of transmitting P-polarized light (light whose vibration direction is parallel to the paper surface) and reflecting S-polarized light (light whose vibration direction is perpendicular to the paper surface). Yes.

  The first polarization beam splitter 26 functions to make the optical axis of the first space-divided beam 5a coincide with the optical axis of the first time-divided beam 7a and to enter the first irradiation head 100, The second polarization beam splitter 27 functions to make the optical axis of the second space-divided beam 5b coincide with the optical axis of the second time-divided beam 7b so as to enter the second irradiation head 101.

  On the other hand, when the optical path switch 4 is OFF, the light travels straight and enters the beam distribution shaper 6a and the beam distribution shaper 6b. The beam distribution shapers 6a and 6b are composed of acousto-optic elements and have a function of deflecting the direction of the laser light 2 in accordance with a command from a higher-level control device (not shown) of the laser processing machine, like the optical path switching device 4. And a function of shaping the pulse waveform into a rectangular shape.

  The laser beam 2 changes its traveling direction as the first time-division beam 7a when the beam distribution shaper 6a is ON, and goes straight when entering the beam distribution shaper 6b when it is OFF. When the beam distribution / shaping device 6b is ON, the laser light 2 changes its traveling direction in the fourth direction as the second time-division beam 7b. Further, when the beam distribution / shaping device 6b is OFF, the laser light 2 goes straight as it is and enters the light shielding body 8, and is converted into heat. Therefore, it is possible to switch between the first time-division beam 7a and the second time-division beam 7b by switching ON / OFF of the beam distribution shapers 6a and 6b.

  In the present embodiment, by switching ON / OFF of the beam distribution shaper 6b, the emission direction of the laser light 2 incident from the beam distribution shaper 6a is changed to the first direction to the light shield 8 and the first direction. Although the beam is deflected in the fourth direction toward the fixed mirrors 15 and 16 deflected by a predetermined angle with respect to the direction 1, the beam distribution shaper 6a does not necessarily switch the emission direction like an optical path deflector. For example, the present invention is established as long as it is an optical device (optical element) having a function of directing the laser beam from the incident beam distribution / shaping device 6 a toward the second irradiation head 101.

  The first time-division beam 7 a is reflected by the fixed mirrors 12, 13, and 14, then passes through the first polarization beam splitter 26 and enters the first biaxial scanner 18. Thereafter, the substrate 24 is irradiated through the same optical path as that of the first space-divided beam 5a. The second time-division beam 7 b is reflected by the fixed mirrors 15 and 16, then passes through the second polarization beam splitter 27 and enters the second biaxial scanner 19. Thereafter, the substrate 25 is irradiated through the same optical path as the second space-divided beam 5b. That is, the fixed mirror 14 is reflected so that the optical axis of the first time-division beam 7a is coaxial with the optical axis of the first space-division beam 5a, and the fixed mirror 16 is reflected in the second time. The split beam 7b is positioned so that the optical axis of the split beam 7b is coaxial with the optical axis of the first space split beam 5b.

  In the first polarization beam splitter 26, the first space-divided beam 5a is reflected by 100% and the first time-divided beam 7a is transmitted by 100%, so that two lights that have passed through different optical paths are put in the same optical path. Can be superimposed without loss. Similarly, in the second polarization beam splitter 27, the second space-divided beam 5b is reflected by 100%, and the second time-divided beam 7b is transmitted by 100%, so that the two lights that have passed through different optical paths are separated. It can be superimposed on the same optical path without loss.

  As shown in FIG. 2, the XY stage 22, when the processing in the processing region 30 by the first biaxial scanner 18 and the second biaxial scanner 19 is completed with respect to the dimension 29 of the substrates 24 and 25, Positioning is performed such that the next work area of the substrates 24 and 25 comes to the scanning area by the first biaxial scanner 18 and the second biaxial scanner 19.

  By the way, there are a burst processing method and a cycle processing method as a method of irradiating one via hole with a pulsed laser beam (hereinafter referred to as “laser pulse”) a plurality of times. In the case of the burst processing method, a predetermined number of laser pulses are continuously irradiated to one hole, and in the case of the cycle processing method, laser pulses are sequentially irradiated to a plurality of via holes in the operating range of the galvano scanner one by one. And repeat a predetermined number of times. In order to shorten the processing time, the burst processing method with a small number of movements of the galvano scanner is advantageous. However, if the laser pulse irradiation interval is short, the processing quality deteriorates due to thermal effects. There are many substrates that are used.

  The half-wave plate 28, the beam splitter 9, the fixed mirror 10, and the first polarizing beam splitter 26 divide the laser light 2 emitted in the second direction from the optical path switch 4 to obtain the first A first optical system that leads to the first irradiation head 100 as the space-divided beam 5a is configured. In addition, the half-wave plate 28, the beam splitter 9, the fixed mirror 11, and the second polarizing beam splitter 27 divide the laser light 2 emitted from the optical path switch 4 in the second direction, so that the second A second optical system that leads to the second irradiation head 101 as the spatially divided beam 5b is configured. A third optical system that guides the laser light 2 emitted from the beam distribution / shaping device 6a in the third direction to the first irradiation head 100 as the first time-division beam 7a by the fixed mirrors 12, 13, and 14. And a fourth optical system that guides the laser light 2 emitted from the beam distribution / shaping device 6b in the fourth direction to the second irradiation head 101 as the second time-division beam 7b by the fixed mirrors 15 and 16. Is configured.

  Next, the operation of the laser processing apparatus of the present invention will be described with reference to FIGS.

  FIG. 3 shows an example of the cycle processing method. FIG. 3A shows scanning by a galvano scanner, and FIG. 3B shows the size of laser pulses to be irradiated and the processing sequence. FIG. 4 is a time chart showing operations of the laser oscillator 1, the optical path switching unit 4, the beam distribution shapers 6a and 6b, and the biaxial scanners 18 and 19.

  Now, holes (hereinafter also referred to as processing positions) 31a, 31b, and 31c in the scanning region 30 of the biaxial scanners 18 and 19 shown in FIG. 3A are processed in this order. Further, as shown in FIG. 3B, three laser pulses are irradiated to one hole. Of the three laser pulses, the first laser pulse is a high-peak intensity laser pulse for processing the glass fiber inside the insulating layer, and the second and third cycles are low peaks for processing only the resin residue. Intense laser pulse. Since the first cycle requires a laser pulse with a high peak intensity, a time-division beam is required, and the second and third cycles may be a laser pulse with a low peak intensity.

First, the operation in the first cycle will be described. In order to stabilize the light intensity and beam profile of the laser beam 2, the laser oscillator 1 is operated at a repetition frequency (1 / T ₁ ) with all of the optical path switch 4 and the beam distribution shapers 6a and 6b turned off. Use pulse oscillation. In this case, the laser light 2 passes through the optical path switching device 4 and the beam distribution shapers 6a and 6b almost 100% and radiates to the light shielding body 8, and then is absorbed by the light shielding body 8 and converted into heat.

Then, only the beam distributor shaper 6a by commands host controller (not shown), in synchronization with the pulse signal of the laser oscillator 1, to select the first time division beam 7a to ON by a time t ₁ Then, one pulse is irradiated to the processing position 31a of the substrate 24. Subsequently, in synchronization with the pulse signal of the laser oscillator 1, and ON the beam distributor shaper 6b by a time t _1, select the second time division beams 7b, 1 pulse to the machining position 31a of the substrate 25 Irradiate. In parallel with this operation, the first biaxial scanner 18 is positioned so that the processing beam can be irradiated onto the processing position 31 b of the substrate 24.

Then, by synchronizing the beam distributor shaper 6a into a pulse signal of the laser oscillator 1, to select the first time division beam 7a to ON by a time t _1, 1 pulse irradiated to the processing position 31b of the substrate 24 To do. In parallel with this operation, the second biaxial scanner 19 is positioned so that the processing beam can be irradiated onto the processing position 31 b of the substrate 25.

Then, by synchronizing the beam distributor shaper 6b into a pulse signal of the laser oscillator 1, select the second time division beams 7b and ON by a time t _1, 1 pulse irradiated to the processing position 31b of the substrate 25 To do. In parallel with this operation, the first biaxial scanner 18 is positioned so that the processing beam can be irradiated onto the processing position 31 c of the substrate 24.

Next, the beam distribution shaper 6 a is synchronized with the pulse signal of the laser oscillator 1, and is turned on for a time t ₁ to select the first time-division beam 7 a and irradiate the processing position 31 c of the substrate 24 with one pulse. To do. In parallel with this operation, the second biaxial scanner 19 is positioned so that the processing beam can be irradiated onto the processing position 31 c of the substrate 25.

Then, by synchronizing the beam distributor shaper 6b into a pulse signal of the laser oscillator 1, to select the first time division beams 7b and ON by a time t _1, 1 pulse irradiated to the processing position 31c of the substrate 25 To do. In parallel with this operation, the first biaxial scanner 19 is positioned so that the processing beam can be irradiated onto the processing position 31 a of the substrate 24. Further, the second biaxial scanner 19 positions so that the processing beam 31 can be irradiated to the processing position 31a of the substrate 25 at the same time as the pulse irradiation to the processing position 31c of the substrate 25 is completed.

Next, the operation in the second cycle will be described. First, the repetition frequency (1 / T ₂ ) of the laser oscillator 1 is changed to the same value as the response frequency (1 / t _g2 ) of the biaxial scanner according to a command from a host controller (not shown).

Next, only the optical path switch 4 is turned on for a time t ₂ in synchronization with the pulse signal of the laser oscillator 1 according to a command from a host controller (not shown), and the first and second spatially divided beams 5a, 5b is irradiated to the processing positions 31a of the substrates 24 and 25, respectively, by one pulse. Thereafter, the first and second biaxial scanners 18 and 19 are positioned so that the processing beam can be irradiated onto the processing positions 31b of the substrates 24 and 25. By repeating this operation for the machining positions 31b and 31c, the machining for the second cycle is completed.

  Since the operation in the third cycle is the same as the operation in the second cycle, description thereof is omitted. When the third cycle of processing is completed, the process moves to the next scan on the XY table, and the same cycle processing is repeated to complete the processing of the entire surfaces of the substrates 24 and 25.

  In the above embodiment, an acousto-optic element is used as the optical path switch 4 and the beam distribution shapers 6a and 6b, but an electro-optic element may be adopted. Further, although the galvano scanner is used as the biaxial scanners 18 and 19, an acousto-optic element or an electro-optic element may be adopted.

  As described above, according to the laser processing apparatus of the present invention, laser processing is not performed by mechanically moving the beam splitter and the mirror as in the prior art, but the optical path switching unit 4 and the beam distribution / shaping unit 6a. Since the laser processing is performed while deflecting the optical path of the laser beam 2 by switching on / off of 6b, it is not necessary to periodically inspect and maintain the positional deviation between the beam splitter and the mirror, and the maintenance inspection becomes easy. Furthermore, since it does not take time to move the beam splitter and the mirror as in the prior art, rapid laser processing can be performed, and the processing efficiency can be improved. In addition, it is possible to provide a laser processing machine capable of processing that requires high peak intensity and high-throughput processing that makes the best use of the high responsiveness of the galvano scanner.

It is a block diagram of the laser processing apparatus which concerns on embodiment of this invention. It is explanatory drawing of the processing area which concerns on embodiment of this invention. It is explanatory drawing of the cycle processing method which concerns on embodiment of this invention. It is explanatory drawing of the time chart which concerns on embodiment of this invention.

Explanation of symbols

1 Laser oscillator 2 Laser (laser light)
4 First optical path deflector (optical path switcher)
5a 1st space division beam 5b 2nd space division beam 6a 2nd optical path deflector (beam distribution shaper)
6b Optical unit, third optical path deflector (beam distribution shaper)
7a First time division beam 7b Second time division beam 9 Beam splitter 12, 13, 14, 15, 16 Fixed mirror 26 First polarization beam splitter 27 Second polarization beam splitter 28 1/2 wavelength plate 100 First 1 laser irradiation section (first irradiation head)
101 2nd laser irradiation part (2nd irradiation head)

Claims (4)

In a laser processing apparatus in which a laser output from a laser oscillator is divided into a time-division beam and a space-division beam and supplied to one of the first and second laser irradiation units,
Sequentially arranged on the optical axis of the laser outputted from the laser oscillator, the incident laser from the laser oscillator is deflected in a first direction or a second direction deflected by a predetermined angle with respect to the first direction. The first optical path deflector that emits, and the second laser that emits the laser from the incident first optical path deflector in the first direction or a third direction deflected by a predetermined angle with respect to the first direction. And an optical device for directing the laser in the first direction from the incident second optical path deflector in the fourth direction toward the second laser irradiation unit,
The laser beam emitted from the first optical path deflector in the second direction is divided, guided to the first laser irradiation unit as a first space-divided beam, and the second space-divided beam as the second space-divided beam. First and second optical systems that lead to the laser irradiation section of
A third optical system that guides the laser emitted from the second optical path deflector in the third direction to the first laser irradiation unit as a first time-division beam;
A fourth optical system that guides the laser emitted from the optical device in the fourth direction to the second laser irradiation unit as a second time-division beam;
A laser processing apparatus, wherein the laser can be selected to be supplied to one or both of the two laser irradiation units. The optical unit emits a third optical path deflecting the laser from the incident second optical path deflector in the first direction or the fourth direction deflected by a predetermined angle with respect to the first direction. Is a vessel,
The laser processing apparatus according to claim 1. The first and second optical systems are arranged on the optical path of the laser emitted in the second direction, and change the polarization direction of the incident laser, and the half-wave plate Comprising a first beam splitter that spatially divides the laser transmitted through
The laser processing apparatus according to claim 1 or 2. The first optical system includes a first polarization beam splitter that is incident on the first laser irradiation unit with an optical axis of the first space-divided beam and an optical axis of the first time-divided beam coincident with each other. Including
The second optical system includes a second polarization beam splitter that is incident on the second laser irradiation unit with the optical axis of the second space-divided beam and the optical axis of the second time-divided beam coincident with each other. Comprising
The laser processing apparatus according to any one of claims 1 to 3.

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