JP2002239772A - Method and device for laser beam machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent decrease in laser beam energy, to prevent the extension of machining time, thus, to decrease a thermal influence in the vicinity of a machining zone, to enable the simultaneous machining of a plurality of positions, and further, to enhance the utility efficiency of a laser beam oscillator. SOLUTION: A time division is applied to the laser beam 2 in midcourse of the optical path 3 synchronously with the oscillation frequency of the laser beam pulse, a plurality of machining positions 5 and 6 of a work 4 to be machined are alternately irradiated with the laser beams 2a and 2b which are divided in time and a plurality of machinings are simultaneously performed, further the laser beams which are divided in time are transmitted in parallel on a plurality of optical paths, and a plurality of positions 5 and 6 of the one or individual works 4 to be machined are irradiated with laser beams by means of individual positioning and condensing units, and the machining is alternatively performed. Thus the purpose is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing method and an apparatus therefor. For example, a beam is irradiated on a workpiece, which is a sheet-like body of a printed circuit board material, through a mask to process holes and the like by transferring a mask pattern. Used for

[0002]

2. Description of the Related Art A conventional apparatus for drilling holes using a laser beam is disclosed in, for example, Japanese Patent Application Laid-Open No. 07-032183. In this apparatus, a pair of X and Y galvanometers b and c are used to position a laser beam a at a processing position of a workpiece m as shown in FIG. Laser beam a emitted from laser oscillator d
Is determined by mirror e and X and Y galvanometers b and c.
It is guided to the workpiece m via the θ lens g. The laser beam a scans the workpiece m in the X and Y directions by swinging about one axis of the X and Y galvanometers b and c, and is positioned at any processing position. lens g deflects a laser beam a deflected around one axis of X and Y by X and Y galvanometers b and c in a direction perpendicular to a processing surface of a workpiece m by fθ characteristics and performs the scanning. Perform at a constant speed. Therefore, the angle at which the X and Y galvanometers b and c swing around one axis is proportional to the moving distance of the laser beam a scanning the workpiece m, and the positioning is accurately performed. Thus, one imaging spot h where the laser beam a is focused on the workpiece m corresponds to one mirror position where the X and Y galvanometers b and c are positioned.

Another laser processing apparatus disclosed in Japanese Patent Application Laid-Open No. 09-248686 uses a hologram,
The laser beam positioned by the galvanometer is condensed on a plurality of processing positions, so that a plurality of imaging spots can be processed simultaneously.

[0004]

By the way, in the above-mentioned conventional laser processing apparatus, a laser oscillator having a laser medium such as YAG, YLF, YVO4 or the like is used to perform a pulse oscillation by opening a Q switch to obtain a fundamental wavelength or When a hole is drilled in a workpiece for a printed wiring board using harmonics, the output is increased by Q-switch oscillation, but the energy cannot be reduced by single pulse irradiation because the energy is still small. For this reason, a plurality of laser pulse irradiations is essential. When the pulse width for performing the laser pulse irradiation is about 150 ns, about 20 laser pulse irradiations are required. At this time, if the frequency of the pulse exceeds 5 kHz, the heat accumulation in the drilled portion tends to increase the thermal effect at the periphery of the drilled hole, and the workpiece m is damaged. FIG. 8 shows a state in which a heat affected layer j is formed around a processing hole i of a workpiece m having a copper foil k. Further, in a method in which a laser beam a is divided into a plurality of pieces by a hologram or a beam splitter and a plurality of holes are processed at the same time, the laser beam a is divided into a plurality of pieces. Since the diameter is reduced to a fraction, the aspect of the processed hole is deteriorated, and the heat-affected layer j tends to be further increased as shown in FIG.

In the method of positioning the laser beam a using the galvanometers b and c, laser oscillation cannot be performed during the operation in which the galvanometers b and c perform positioning, which results in a processing loss time. In addition, the utilization efficiency of the laser oscillator decreases.

The main object of the present invention is to reduce the energy of the laser beam and to extend the processing time, and
It is an object of the present invention to provide a laser processing method and a laser processing apparatus capable of processing a plurality of positions in parallel with little thermal influence on a processing portion, and further provide a laser processing method and a laser processing apparatus capable of improving the utilization efficiency of a laser oscillator. Is to do.

[0007]

In order to achieve the above object, a laser processing method according to the present invention focuses a laser beam emitted from a laser oscillator and irradiates a workpiece with a laser pulse to perform processing. In order to perform the processing, the laser beam is time-divided in synchronization with the laser pulse oscillation frequency, and the time-divided laser beam is alternately applied to a plurality of processing positions of a workpiece to perform a plurality of processings.

In such a configuration, a plurality of processing positions of a workpiece are irradiated with laser pulses to perform processing in parallel.
The laser beam irradiated to a plurality of processing positions is time-divided in the middle of the optical path, and the entire amount of the laser beam oscillated from the laser oscillator at each time is irradiated to each processing position. Therefore, there is no decrease in the length and the time is not prolonged, so that the processing can be performed with less heat influence on the periphery of the processing portion.

A laser processing apparatus for achieving such a method includes a laser oscillator, a transmission optical system for transmitting a laser beam emitted from the laser oscillator and condensing the laser beam on a processing position of a workpiece, and a laser oscillator. And a control device that performs processing by irradiating a laser beam from a laser beam to a processing position, and a time-division unit that time-divides the laser beam in synchronization with a laser pulse oscillation frequency,
The control device is characterized in that a plurality of processing positions of a workpiece are alternately irradiated with split beams of a time-divided laser beam to perform a plurality of processings. It can be performed stably.

The time division means comprises a mirror for time-dividing the laser beam by swinging the angle, and the control unit synchronizes the angle of the mirror with the laser pulse oscillation frequency so that laser oscillation occurs at both ends of the swing width of the mirror. Accordingly, in the relationship between the mirror and the laser pulse oscillation, the oscillation frequency of the mirror is small with respect to the high-frequency laser pulse oscillation, and the laser beam is irradiated at both ends of the oscillation width. Can be regarded as substantially stopped, time-division and alternate irradiation at high speed can be automatically and stably achieved without control for actually stopping the mirror.

A laser oscillator emits a linearly polarized laser beam, and the time division means comprises a combination of an electro-optical polarizer and a polarizer arranged before and after on an optical path. By rotating the angle with respect to the linearly polarized light, the laser beam can be time-divided into reflected light and transmitted light at the polarizer, thereby shortening the time required for multiple processing, The utilization efficiency of the laser oscillator is further improved.

The transmission optical system is composed of one optical unit, and laser beams of a plurality of time-divided optical paths are transmitted in parallel to irradiate a plurality of positions on a workpiece to perform processing alternately. As a result, the apparatus can be simplified, and the use of different optical units eliminates the influence of the mutual position and orientation shift and the difference in characteristics, thereby enabling more accurate processing.

[0013] The transmission optical system has two positioning and focusing units, and the control device transmits laser beams of a plurality of optical paths that are time-divided individually and in parallel, and separate optical units for processing one or more workpieces. By irradiating a plurality of positions to perform processing alternately, it is possible to perform the positioning of the time-divided laser beam and the processing based thereon at timings opposite to each other, thereby making the laser oscillator almost continuous. And oscillate at the same time to perform multiple processing alternately.
The use efficiency of the laser oscillator can be increased, and the processing speed can be further improved by eliminating the processing time loss.

If the laser oscillator controls the laser pulse oscillation by opening a shutter means such as a Q switch, it is possible to cope with the laser pulse oscillation irradiation by a general technique conventionally used. it can.

Further features and operations of the present invention will become apparent from the following detailed description and drawings. Each feature of the present invention is solely as much as possible,
Alternatively, various combinations can be used in combination.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing method and apparatus according to some embodiments of the present invention will be described below in detail with reference to FIGS. The following embodiments are specific examples of the present invention and do not limit the technical scope of the present invention.

The embodiment of the present invention is an example of a case where a plurality of holes are formed by a laser beam using a sheet-like body as a material of a printed circuit board as a workpiece. However, the present invention is not limited to this. In the case where a plurality of holes are drilled in any workpiece, and in the case where a plurality of holes to be processed are dispersed in one workpiece, The present invention is also effective when applied to a plurality of workpieces, and these are also included in the scope of the present invention. The processing is not limited to the hole processing.

(Embodiment 1) As shown in FIG. 1, a laser processing method according to Embodiment 1 focuses a laser beam 2 emitted from a laser oscillator 1 to form a sheet-like body 4 as a workpiece.
Drilling is performed by irradiating laser pulses to At this time, the laser beam 2 is time-divided into beams 2a, 2b,... In the middle of the optical path 3 in synchronization with the laser pulse oscillation frequency, and the time-divided divided beams 2a, 2b,. Irradiation is alternately performed on a plurality of processing positions 5, 6 and the like to perform a plurality of hole processing. Therefore, as a laser processing device, the laser oscillator 1 and the laser beam 2 emitted from the laser oscillator 1 are transmitted to process the processing positions 5, 6,
.. a transmission optical system 7 having the optical path 3 for condensing the light;
Split beam 2 of laser beam 2 from laser oscillator 1
a control device 8 that irradiates laser pulses a and 2b to the processing positions 5 and 6 alternately to perform hole drilling, and a time division means 9 that divides the laser beam 2 in the optical path 3 in synchronization with the laser pulse oscillation frequency. And the control device 8 controls the laser beam 2
The time-divided split beams 2a, 2b,... Are alternately distributed to a plurality of processing positions 5, 6,. In order to form an irradiation spot in accordance with the size and shape of the hole to be processed, a mask 21 for shaping the cross-sectional shape of the laser beam 2 is used. Will be However, it is not limited to this.

In the above, in order to irradiate the laser pulse to the plurality of processing positions 5, 6,... Of the sheet-like body 4 and perform the drilling in parallel, the laser beam 2 irradiated with the laser pulse to the plurality of processing positions Are divided beams 2a and 2b which are time-divided and distributed in the middle of the optical path.
In the steps 6,..., The entire amount of the laser beam 2 oscillated from time to time is irradiated from the laser oscillator 1 so that the drilling is performed without lowering the energy or prolonging the time. be able to.

The basic structure of the transmission optical system 7 shown in FIG. 1 is the same as that of the above-mentioned conventional case, and the transmission optical system 7 is formed by a suitable number of mirrors 11 and X and Y galvanometers 12 and 13 via a fθ lens 14 through a sheet-like body. Lead to 4. The X and Y galvanometers 12 and 13 deflect the split beams 2a and 2b of the laser beam 2 in the X and Y2 directions by swinging about one axis thereof to scan the sheet-like body 4 in the XY2 directions, and , 6,..., And can be freely distributed to each of the processing positions 5, 6,. Here, X, Y galvanometers 12, 1
3 is a distributing means 1 for distributing the split beams 2a and 2b.
0, the control device 8 controls the pulse oscillation of the laser oscillator 1 and the time division operation of the time division means 9 in synchronization with each other to divide the divided beams 2a, 2b,. Laser beam pulse irradiation for drilling holes that are alternately illuminated in the order of... The pulse oscillation of the laser oscillator 1 is performed by controlling the opening operation of shutter means such as the Q switch 33 by the control device 8. In this case, it is preferable to use the laser oscillator 1 having a laser medium such as YAG, YLF, or YVO4 described above.

Lens 14 is an X, Y galvanometer 1
The split beams 2a and 2b of the laser beam 2 deflected in the X and Y directions by the oscillation about one axis 2 and 13 are deflected in a direction perpendicular to the processing surface of the sheet-like body 4 by the fθ characteristic and the scanning is performed. Perform at a constant speed. Accordingly, the angle at which the X and Y galvanometers 12 and 13 swing about one axis and the moving distance of the divided beams 2a and 2b of the laser beam 2 scanning the sheet 4 are proportional to each other. It is possible to accurately position and form an image by allocating to each of the processing positions 5, 6,.... Thus, one imaging spot where the split beams 2a and 2b are focused on the sheet 4 corresponds to one mirror position where the X and Y galvanometers 12 and 13 are positioned. The plurality of processing positions 5, 6,... Are alternately irradiated with the divided beams 2a, 2b, and the holes are drilled in parallel automatically and stably.

As shown in FIG. 2, the time-division means 9 of the first embodiment converts the laser beam 2 by a resonance type mirror scanner 31 which oscillates at a constant frequency with a sinusoidal vibration around one axis as shown in FIG. , As shown in FIG. 2 (a). As an example, the mirror scanner 31 has a frequency of 4 kHz. A condensing lens oscillated by the laser oscillator 1 and having a focal length f = 1000 mm (provided inside or outside the laser oscillator 1) 3
The laser beam 2 transmitted through the mirror scanner 3
1 mm from the condenser lens 34
Positioning is performed in a time division manner with respect to two different openings of the mask 21 provided at distant positions. At this time, the split beams 2a and 2b have a diameter of 300 as shown in FIG.
The swing width of the mirror scanner 31 is set so that the openings 21a and 21b of μm enter the laser beam irradiation units 2a1 and 2b1 of approximately 500 μm. .. Are both shaped through one of the openings 21a and 21b of the mask 21, and the fθ lens 14 at a distance of 1000 mm therefrom.
Thereby, an image is formed on the sheet-like body 4.

The operation of the mirror scanner 31 is schematically shown in FIG. In FIG. 3A, the mirror scanner 31 is used.
Laser beam 2 that is deflected by the laser beam and moves through mask 21
Is plotted on the vertical axis, and the elapsed time is plotted on the horizontal axis.
The positions marked with □ and ● are both ends of the swing width of the mirror scanner 31 and are positions where the mirror scanner 31 stops momentarily. When the control device 8 controls the pulse oscillation of the laser oscillator 1 in synchronization with this timing, the pulse width becomes 5
The vibration frequency of the mirror scanner 31 is very slow at 4 kHz for 0 to 150 ns. Thus, the mirror scanner 31 can be regarded as substantially stopped while the laser pulse oscillation is being performed.

As described above, in order to synchronize the angle of the mirror scanner 31 and the frequency of laser oscillation so that laser oscillation occurs at both ends of the swing width of the mirror scanner 31, there is no control to actually stop the mirror scanner 31. Time-division and alternate irradiation at high speed.

The frequency of the emission command signal of the laser oscillator 1 shown in FIG. 3B is 8 kHz, which is twice the frequency of the mirror scanner 31. The light emission frequency at the processing position is the same as the frequency of the mirror scanner 31 and is 4 kHz. For this reason, even if the pulse oscillation frequency of the laser oscillator 1 is increased to increase the entire hole processing speed, the processing speed at each processing position is equal to the conventional processing speed at which the laser beam 2 is not branched. Even if a plurality of holes are formed in parallel, the heat-affected layer around the holes becomes about 5 to 10 μm, which is the same as the conventional case in which the laser beam 2 is not branched.

In the first embodiment, as shown in FIG.
Laser beams 2 of a plurality of optical paths that are time-divided into a system are transmitted in parallel, and radiated to a plurality of positions of the sheet-like body 4 by a transmission optical system 7 that forms the same optical unit, thereby performing hole machining alternately. Therefore, the apparatus becomes simpler, and there is no influence due to mutual position and posture shift and characteristic difference due to transmission of the laser beam 2 time-divided into two systems by different optical units. Can be.

(Embodiment 2) This embodiment 2 uses a laser oscillator 41 for emitting a linearly polarized laser beam 42 as shown in FIG. The time division means 9 is constituted by a combination of the polarizer 44 and the polarizer 45, and the laser beam 42
Is time-divided into two systems. The angle of the laser beam 42 with respect to the linearly polarized light is electrically controlled by the control device 8 to rotate the electro-optical polarizer 44 at high speed. The laser beam 42 is rapidly converted into a divided beam 42a reflected by the polarizer 45 and a transmitted divided beam 42b. Can be time-shared. As a result, the time required for processing a plurality of holes becomes shorter, and the utilization efficiency of the laser oscillator 41 is further improved.

(Embodiment 3) As shown in FIG. 5, in Embodiment 3, as in Embodiment 2, a laser beam 42 emitted from a laser oscillator 41 is divided into two systems of split beams 42a by an electro-optic polarizer 44. , 42b. However, the divided two divided beams 42a and 42b are handled in their optical paths 43a and 43b by individual positioning and focusing units 47a and 47b having the mask 21, the X and Y galvanometers 12 and 13, and the fθ lens 14. Processing positions 5 and 6 dispersed in one sheet 4
The drilling is performed in parallel under the control of the control device 8.

FIG. 6 (a) shows a state in which one of the positioning and focusing units 47a is drilled. First,
Drilling is performed by a plurality of laser pulse oscillations while the X and Y galvanometers 12 and 13 are stopped in the positioning state. The time required for this hole drilling is, for example, about 1 to 7 ms. Subsequently, the X and Y galvanometers 12 and 13 move to perform positioning to the next processing position. The time for this is, for example, about 1 to 20 ms.
For this reason, the operation time for positioning the X and Y galvanometers 12 and 13 and the time required for drilling have substantially the same time interval. Thereby, when one set of the positioning condensing unit 47b is provided as shown in FIG. 5 and drilling is performed under the control of FIG. 6A as shown in FIG. In the control of FIG.
When the positioning operation by the Y galvanometers 12 and 13 is completed, and the positioning is being performed by the control of FIG. 6A, the hole machining is performed by the control of FIG. 6B.

As described above, as shown in FIGS.
By setting and controlling the positioning operation and the hole drilling operation in the two positioning light collecting units 47a and 47b to have opposite timings, the laser peak is reduced by half as in the case where the laser beam 42 is split by the beam splitter. Does not occur, and the cause of the poor aspect ratio of the machined hole can be eliminated. As a result, the oscillation time of the laser oscillator 41 in the third embodiment is almost twice as long as the conventional case where laser oscillation is performed only after the positioning operation. Therefore, the oscillation efficiency is increased, and it is possible to contribute to the improvement of the processing speed. Further, by performing processing using a pulse laser having the same peak power as in the conventional case in which branching is not performed, the aspect ratio of a processed hole is the same as in the conventional case in which branching is not performed.

[0031]

As is apparent from the above description, according to the laser processing method and apparatus of the present invention, each processing position is oscillated from the laser oscillator at each time and the entire amount of the laser beam is pulse-irradiated. Therefore, the processing can be performed without lowering the energy or extending the time due to the reduction of the energy, and therefore, the influence of the heat around the processing portion can be reduced.

Further, separately, the positioning of the time-divided split laser beam and the processing thereby can be performed at timings opposite to each other, and the laser oscillator is oscillated almost continuously to perform a plurality of processings alternately. The utilization efficiency can be increased, and the processing speed can be further improved by eliminating the processing time loss.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram illustrating a laser processing method and apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation of the time division means of FIG. 1;

3A is a graph showing a synchronous relationship between laser beam oscillation and split beam positioning in the method and apparatus of FIG. 1, and FIG. 3B is a time chart showing a control state of laser beam oscillation timing. .

FIG. 4 is a configuration diagram of a main part showing a laser processing method and apparatus according to a second embodiment of the present invention.

FIG. 5 is an overall configuration diagram illustrating a laser processing method and apparatus according to a third embodiment of the present invention.

FIG. 6 is a timing chart of positioning and drilling in the method and apparatus of FIG. 5;

FIG. 7 is an overall configuration diagram showing a conventional laser processing apparatus.

8 (a) is a plan view and FIG. 8 (b) is a sectional view showing a state of drilling by the apparatus of FIG. 7;

FIG. 9 shows a state of drilling by another conventional apparatus, in which (a) is a plan view and (b) is a sectional view.

[Description of Signs] 1, 41 Laser oscillator 2, 42 Laser beam 2a, 2b, 42a, 42b Divided beam 3, 43 Optical path 4 Sheet 5, 6, Processing position 7 Transmission optical system (optical unit) 8 Control device 9 Dividing means 11 Mirror 12 X Galvanometer 13 Y Galvanometer 14 fθ lens 21 Mask 33 Q switch 44 Electro-optical polarizer 45 Polarizer 47a, 47b Positioning and focusing unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01S 3/00 H01S 3/00 B // B23K 101: 42 B23K 101: 42 F term (Reference) 2H041 AA11 AB14 AC04 AZ06 2H079 AA03 BA01 BA02 CA24 HA16 KA05 4E068 CA03 CA04 CD04 CD07 CD12 CE03 5F072 AB01 JJ02 KK05 MM05 MM17 SS06 YY06

Claims (7)

[Claims] 1. A laser processing method for converging a laser beam emitted from a laser oscillator and irradiating a workpiece with a laser pulse, wherein the laser beam is time-divided in synchronization with a laser pulse oscillation frequency. A laser processing method comprising: irradiating time-division laser beams to a plurality of processing positions of a workpiece alternately to perform a plurality of processings in parallel. 2. A laser oscillator, a transmission optical system for transmitting a laser beam emitted from the laser oscillator and condensing the laser beam on a processing position of a workpiece, and irradiating a laser beam from the laser oscillator to a processing position with a laser pulse. A laser processing device comprising: a control device for performing processing by performing time-division processing; and a time-division means for performing time-division synchronization of the laser beam with a laser pulse oscillation frequency. A laser processing apparatus, wherein a plurality of processing positions of an object are alternately irradiated to perform a plurality of processing. 3. The time-sharing means includes a mirror for time-sharing a laser beam by swinging an angle, and the control device controls the laser so that laser oscillation occurs at both ends of the swing width of the mirror.
The laser processing apparatus according to claim 2, wherein the angle of the mirror and the laser pulse oscillation frequency are synchronized. 4. A laser oscillator emits a linearly polarized laser beam, the time division means comprises a combination of an electro-optical polarizer and a polarizer arranged before and after on an optical path, and the control device controls the laser by the electro-optical polarizer. 3. The laser beam is time-divided into reflected light and transmitted light from a polarizer by rotating an angle of the beam with respect to linearly polarized light.
The laser processing apparatus according to item 1. 5. A transmission optical system comprising a single optical unit, wherein laser beams of a plurality of time-divided optical paths are transmitted in parallel to irradiate a plurality of positions on a workpiece to perform processing alternately. Item 5. The laser processing apparatus according to any one of Items 2 to 4. 6. The transmission optical system has two positioning light-collecting units, and the controller transmits laser beams of a plurality of time-division optical paths individually and in parallel, and one or more workpieces are processed by the individual optical units. The laser processing apparatus according to any one of claims 2 to 4, wherein processing is performed alternately by irradiating a plurality of positions on the object. 7. The laser processing apparatus according to claim 2, wherein the laser oscillator controls the pulse oscillation of the laser beam by opening shutter means such as a Q switch.