JP2004034120A - Repetitive laser machining method and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rapidly perform cycle mode machining on machining points of a plurality of machining areas. <P>SOLUTION: A plurality of repetitive laser machining are performed to the same machining point of each machining area without scanning laser beams by switching the polarized state of laser beams with which the machining areas 31 and 32 for each machining area are irradiated by using an electro-optic element (EOM) 12. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser repetitive processing method and apparatus, and in particular, intermittently irradiates laser light to processing points in a plurality of processing areas of a processing target suitable for use in a laser drilling machine for processing a printed circuit board. Thus, the present invention relates to an improvement in a laser repetitive processing method and apparatus in which repetitive processing is performed a plurality of times.
[0002]
[Prior art]
In order to accurately form through-holes and via-holes with a diameter of 0.1 mm or less, which have been downsized with recent miniaturization and higher functionality of printed circuit boards, a pulse oscillation type laser beam is used to reduce the diameter. Laser drilling machines that form holes have been put into practical use.
[0003]
In this laser drilling machine, in general, in order to increase the work efficiency, a plurality of processing heads are used to simultaneously drill holes in a plurality of processing areas of a printed wiring board. The apparatus is designed to reduce the size and cost.
[0004]
Furthermore, in order to prevent energy reduction after energy splitting by energy splitting (halved in the case of splitting two) and to accurately control energy after splitting, as shown in FIG. ) Is switched by, for example, the electro-optic element (EOM) 12 so that the direction of the linearly polarized light is changed every time so that the P wave and the S wave are alternately output and installed on the exit side of the EOM 12. It is considered that the polarization beam splitter 14 splits the P wave and the S wave into two branches.
[0005]
The laser beams 15 and 17 branched by the polarizing beam splitter 14 are changed in direction either directly or by a mirror 16, and are respectively galvano scanners for processing a first axis (referred to as Z1 axis) (hereinafter referred to as Z1 galvo). 18 and a second processing head including a galvano scanner (hereinafter referred to as Z2 galvano) 20 for processing a second axis (referred to as Z2 axis), and supplied to the galvanos 18, 20 respectively. For example, by two galvanometer mirrors 26 and 28 (see FIG. 2) included, for example, in the X-axis direction perpendicular to the paper surface and parallel to the paper surface, corresponding to the processing position on the processing object (referred to as a workpiece) 8 The workpiece 8 is scanned by being scanned in the Y-axis direction and applied to the surface of the workpiece 8 via the fθ lenses 22 and 24. In FIG. 1, 30 is a control device.
[0006]
As shown in detail in FIG. 2, the galvanometers 18 and 20 respectively include a first galvanometer mirror 26 for scanning the laser beams 15 and 17 branched by the polarization beam splitter 14 in the X-axis direction perpendicular to the paper surface. The second galvanometer for scanning the beam scanned in the X-axis direction by the first galvanometer mirror 26 in the Y-axis direction perpendicular to the X-axis direction and parallel to the paper surface and entering the fθ lenses 22 and 24. A mirror 28 is provided. In FIG. 2, 27 and 29 are motors for rotating the galvanometer mirrors 26 and 28, respectively.
[0007]
In such time division processing, the laser light oscillated by the laser oscillator 10 is time-divided into S wave and P wave by the EOM 12 controlled by the control device 30, and the S wave is supplied to the Z1 galvano 18, for example. Then, the machining area underneath is machined, and the P wave is supplied to the Z2 galvano 20 to machine the machining area under it.
[0008]
When processing by such laser irradiation, when the hole quality varies due to light scattering by the plume rising from the processing point, or when the hole quality deteriorates due to heat accumulation at the processing point, or glass fiber When a required hole cannot be penetrated by a single irradiation, such as in the case of processing a composite material such as a resin, a hole is made by repeating a plurality of irradiations.
[0009]
The method of multiple times of irradiation is the method of staying in the same hole, irradiating multiple times, moving to the next hole (generally called burst mode processing), and sequentially drilling one round in a certain processing area It is divided into a method of performing multiple times (generally referred to as cycle mode processing) and a combination thereof (generally referred to as combination mode processing). These processing methods are appropriately used depending on the material of the substrate, the laser beam to be used, the pulse shape, etc., and the method by cycle mode processing is described in, for example, JP-A-11-192571 and JP-A-11-284411. Yes.
[0010]
In the cycle mode machining (precisely combination mode machining), for example, as shown in FIG. 3, a Z1 axis machining area (referred to as Z1 machining area) 31 and a Z2 axis machining area (referred to as Z2 machining area) 32 are provided. When there are three machining points (1), (2), (3), (1) ', (2)', and (3) ', conventionally, as shown in FIG. As the Z1 axis side, the machining point {circle around (1)} of the Z1 machining area 30 is machined in the burst mode. Next, with the EOM 12 as the Z2 axis side that passes the P wave, the machining point {circle around (1)} of the Z2 machining area 32 that has been positioned by operating the Z2 galvano 20 during the Z1 axis machining is machined in the burst mode. Next, the EOM 12 is set to the Z1 axis side again, the machining point {circle around (2)} of the Z1 machining area 31 where the Z1 galvano 18 is moved and positioned during the Z2 axis machining is machined, and so on. To perform positioning. Furthermore, in cycle mode machining in which the same machining point (1) needs to be machined again at intervals, (1) → (1) ′ → (2) → (2) ′ → (3) → ▲ As in the case of 3 ▼ ′ → (1), after the processing of the processing point (3) ′ is completed, the processing of the processing point (1) is resumed.
[0011]
[Problems to be solved by the invention]
However, conventionally, since the galvano scanner is also used for the cycle of the processing point, the operation of the galvano scanner is required for the number of cycles, and the processing speed is low.
[0012]
The present invention has been made to solve the above-described conventional problems, and it is an object of the present invention to be able to rapidly perform cycle mode machining in which machining is intermittently performed at the same machining point.
[0013]
[Means for Solving the Problems]
In the present invention, when the laser beam is intermittently irradiated to the processing points of the plurality of processing areas of the processing object and the processing is repeatedly performed a plurality of times, the polarization state of the laser light irradiated to each processing area is electrically changed. By switching to each processing area using an optical element, the above-mentioned problem is solved by performing a plurality of repeated processings on the same processing point in each processing area without scanning the laser beam. is there.
[0014]
The present invention is also a laser repetitive processing apparatus for intermittently irradiating a laser beam to processing points of a plurality of processing areas of a processing object and repeatedly processing the plurality of times, respectively, and irradiating each processing area. An electro-optical element for switching the polarization state of the laser light for each processing area, and a polarization beam splitter for guiding the laser light emitted from the electro-optical element to the corresponding processing area according to the polarization state; By switching the polarization state of the laser light irradiated to each processing area for each processing area using the electro-optic element, the same processing point in each processing area can be obtained without scanning the laser light. The above-mentioned problem is solved in the same manner by repeatedly performing a plurality of times.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
In the present embodiment, similarly to the comparative example shown in FIG. 1, the polarization state of the output laser light of the laser oscillator 10 is switched for each processing area using the electro-optic element (EOM) 12, and the laser emitted from the EOM 12 is used. The lights 15 and 17 are guided to the corresponding processing areas 31 and 32 according to the polarization state by the polarization beam splitter 14.
[0017]
At this time, for example, when the S wave is reflected by the polarization beam splitter 14 and the P wave is transmitted, the processing points {circle around (1)}, {circle around (5)} positioned by the galvanos 18 and 20 as shown in FIG. In 1 ▼ ′, by switching the EOM 12, for example, the S wave first passes through the EOM 12 to process the machining point (1) of the Z1 axis in the burst mode, and then the EOM 12 is switched without operating the galvano scanner. Machining point (1) 'of Z2 axis is processed in burst mode by wave, EOM12 is switched again for cycle mode machining, machining point (1) of Z1 axis is reprocessed by S wave, and EOM12 is switched again. Then, the machining point {circle around (1)} on the Z2 axis is reworked by the P wave.
[0018]
After the cycle mode machining of the machining points (1) and (1) ′ is repeated as many times as necessary in this way, the galvanos 18 and 20 are operated to position to the next machining points (2) and (2) ′. The laser irradiation of the Z1 axis machining point {circle around (2)} by the S wave and the laser irradiation of the Z2 axis machining point {circle around (2)} by the P wave are repeated a predetermined number of times by switching the EOM 12.
[0019]
In this way, the cycle mode machining of each machining point can be completed only by switching by the EOM 12 without operating the galvanos 18 and 20. The switching time of the EOM 12 is as fast as several microseconds to several tens of microseconds, and it is not necessary to pause the laser pulse as in the case of switching by galvano. it can.
[0020]
The cycle interval t of cycle mode machining on each axis is set to a predetermined time or longer that can prevent light scattering due to plume from the machining point and deterioration of hole quality due to heat accumulation at the machining point.
[0021]
In the above-described embodiment, the present invention has been applied to cycle mode machining in combination mode machining, but the application target of the present invention is not limited to this, and cycle mode machining not using burst mode machining together, Applicable.
[0022]
In the above embodiment, the present invention is applied to the biaxial machining. However, the application target of the present invention is not limited to this, and the EOM 13 and the polarization beam splitter as in the second embodiment shown in FIG. By increasing the number of 15, it can be similarly applied to three or more axes.
[0023]
In the above embodiment, the present invention is applied to a laser drilling machine. However, the application target of the present invention is not limited to this, and it is obvious that the present invention can be similarly applied to general laser processing machines.
[0024]
【The invention's effect】
According to the present invention, it is possible to perform cycle mode machining of the same machining point without operating the galvano scanner, and it is possible to quickly perform cycle mode machining that conventionally required time without reducing the speed. Become.
[0025]
Therefore, rapid processing of composite materials that require cycle mode processing, such as resin containing glass fiber, while preventing variations in hole quality caused by light scattering from the plume from the processing point and deterioration of hole quality due to heat accumulation Is possible.
[Brief description of the drawings]
FIG. 1 is an optical path diagram showing a configuration example of a laser drilling machine having two machining heads. FIG. 2 is a front view showing a specific configuration example of a galvano scanner used in the laser drilling machine. FIG. 4 is a time chart showing examples of signal waveforms at various parts in cycle mode machining of a comparative example. FIG. 5 is a time chart showing operation waveforms at various parts in the first embodiment of the present invention. FIG. 6 is an optical path diagram showing the configuration of the second embodiment of the present invention.
8 ... Workpiece (workpiece)
10 ... Laser oscillator 12 ... Electro-optical element (EOM)
14 ... Polarizing beam splitter 18, 20 ... Galvano scanner

Claims (2)

When intermittently irradiating the laser beam to the processing points of the plurality of processing areas of the processing object and repeatedly processing each of them multiple times,
By switching the polarization state of the laser light irradiated to each processing area for each processing area using an electro-optic element, the same processing point in each processing area can be performed multiple times without scanning the laser light. A laser repetitive processing method characterized by performing repetitive processing. A laser repetitive processing apparatus for intermittently irradiating a laser beam to a processing point of a plurality of processing areas of a processing object and repeatedly processing a plurality of times,
An electro-optic element for switching the polarization state of the laser light irradiated to each processing area for each processing area;
A polarization beam splitter for guiding laser light emitted from the electro-optic element to a corresponding processing area according to the polarization state;
By switching the polarization state of the laser light applied to each processing area for each processing area using the electro-optic element, the same processing point in each processing area is scanned multiple times without scanning the laser light. Laser repetitive processing apparatus characterized by performing repetitive processing.

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