JP2009006369A - Laser beam machining apparatus and laser beam machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus and a laser beam machining method which can perform high quality machining. <P>SOLUTION: (a) With all energy of an incident laser beam directed to a first route by a beam deflector, a laser pulse is emitted from a laser beam source and made incident on the beam deflector. (b) A relationship between the lapse of time from the rising point of time of the laser pulse and the light intensity is acquired during the transient period of the light intensity reaching a stationary state. (c) On the basis of the acquired relationship, an emission efficiency is determined and, after the light intensity of the laser pulse reaches the stationary state, the beam deflector is caused to emit the laser beam of the energy of the determined emission efficiency portion along a second route, and to emit the laser beam of the residual energy along the first route. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus that performs processing by irradiating a workpiece with a laser beam, and a laser processing method.

  An invention of a laser processing apparatus and a laser processing method capable of stabilizing processing quality and preventing processing defects has been disclosed (for example, see Patent Document 1).

  In the laser processing described in Patent Document 1, energy is detected using a detector for the first part of laser light emitted from a laser oscillator, and it is determined by a determination device whether the energy is within a predetermined energy range. To do. After the determination, when the energy is within a predetermined energy range, the optical path deflecting unit is operated to irradiate the processing unit with the laser beam. If it is not within the predetermined energy range, the optical path deflecting means is not operated and the laser beam is not irradiated onto the processing portion.

  However, in this laser processing, the energy variation within the predetermined range cannot be controlled.

  Further, an invention relating to laser processing that performs processing with a constant processing quality by controlling the transmittance of an acousto-optic deflector (AOD) to stabilize the energy of the laser beam is disclosed (for example, , See Patent Document 2).

JP 2004-25292 A JP 2005-161329 A

  An object of the present invention is to provide a laser processing apparatus that realizes high-quality processing.

  Moreover, it is providing the laser processing method which implement | achieves a high quality process.

  According to an aspect of the present invention, when a laser light source that emits a pulsed laser beam and an emission efficiency is commanded from outside, a laser beam having an energy corresponding to the commanded emission efficiency is included in the energy of the incident laser beam. A beam deflector that emits the laser beam of the remaining energy along the second path and detects the light intensity of the laser beam emitted along the second path. A detector, a first optical system that causes the laser beam emitted along the first path to enter the first processing region, and a signal indicating the light intensity detected by the detector are input, A control device for controlling a laser light source and a beam deflector, wherein the control device is in a state in which (a) the beam deflector directs the total energy of the incident laser beam to the second path, in front A step of emitting a laser pulse from a laser light source; and (b) a step of acquiring a relationship between a light intensity and an elapsed time from a rising point of the laser pulse during a transient period until the light intensity reaches a steady state. (C) determining the emission efficiency based on the acquired relationship, and instructing the beam deflector on the determined emission efficiency after the light intensity of the laser pulse has reached a steady state; A laser processing apparatus for performing is provided.

  According to another aspect of the present invention, (a) a laser pulse is emitted from a laser light source in a state in which all energy of a laser beam incident on the beam deflector is directed to the first path, and the beam deflector And (b) acquiring the relationship between the elapsed time from the rising point of the laser pulse and the light intensity during a transient period until the light intensity reaches a steady state, and (c) Based on the relationship, the emission efficiency is determined, and after the light intensity of the laser pulse reaches a steady state, the laser beam having the energy corresponding to the determined emission efficiency is sent to the beam deflector as the first path. And a step of emitting a laser beam of the remaining energy along the first path, and a step of emitting the laser beam along the first path.

  ADVANTAGE OF THE INVENTION According to this invention, the laser processing apparatus which implement | achieves a high quality process can be provided.

  In addition, a laser processing method that realizes high-quality processing can be provided.

  FIG. 1 is a schematic diagram illustrating a laser processing apparatus according to an embodiment. The laser processing apparatus according to the embodiment includes a laser light source 10, an AOD 11, a partial reflection mirror 12, a beam block 13, a detector 14, a folding mirror 15, a control device 17, a trigger signal generator 18, and an AOD control signal generator 19. Consists of. The control device includes a storage device 17a, for example, a memory.

  In response to an external control signal (trigger signal), for example, a pulse laser beam Lb having a pulse width of 100 μsec is emitted from the laser light source 10. The pulse laser beam Lb is incident on the AOD 11. The AOD 11 can receive a high-frequency electric signal (AC voltage) given from the outside and deflect and emit the pulsed laser beam Lb.

  When a high-frequency electrical signal (AC voltage) is applied to the AOD 11, an ultrasonic coarse / fine wave synchronized with the electrical signal is generated in the AOD 11. The pulsed laser beam Lb is deflected (diffracted) by the action of the dense wave as a diffraction grating.

  The diffraction angle of the pulse laser beam Lb depends on the frequency of the dense wave. The diffraction angle can be continuously changed by continuously changing the frequency of the dense wave. The frequency of the dense wave can be controlled by changing the frequency of the electric signal. When no electrical signal is applied to the AOD 11, the pulsed laser beam Lb is not diffracted and goes straight through the AOD 11.

  Further, by changing the amplitude of the applied high frequency electrical signal, the diffraction efficiency of the AOD 11 can be changed, and the laser intensity (energy) of the pulse laser beam Lb emitted from the AOD 11 can be changed.

  For example, when an incident laser beam is diffracted (deflected) with a diffraction efficiency of 0.7, 70% of the incident laser beam energy is deflected and emitted, and the laser beam has 30% energy. Goes straight ahead.

  A pulsed laser beam Lb that is applied with an electric signal of a predetermined frequency to the AOD 11 and is deflected in a predetermined direction and emitted from the AOD 11 is indicated as a pulsed laser beam Lba in this drawing. The pulse laser beam Lba is reflected by the folding mirror 15 and enters the processing region 16. Laser processing such as substrate drilling is performed by the pulse laser beam Lba incident on the processing region 16.

  The pulse laser beam Lb that travels straight through the AOD 11 is shown as a pulse laser beam Lbb in this drawing. The pulse laser beam Lbb is incident on the partial reflection mirror 12.

  The partial reflection mirror 12 transmits most of the incident pulse laser beam Lbb and reflects the remaining part. The pulse laser beam Lbb transmitted through the partial reflection mirror 12 is shown as a pulse laser beam Lbc in this drawing. The pulsed laser beam Lbc enters the beam block 13 and is absorbed by it.

  The pulse laser beam Lbb reflected by the partial reflection mirror 12 is shown as a pulse laser beam Lbd in this drawing. The pulsed laser beam Lbd is incident on the detector 14.

  The detector 14 detects the laser intensity (light intensity) of the incident pulse laser beam Lbd. Data on the detected laser intensity is transmitted to the control device 17. The control device 17 determines the diffraction efficiency of the AOD 11 based on the laser intensity data transmitted from the detector 14, and issues a high frequency electrical signal (AC voltage) generation command to the AOD control signal generator 19. The AOD control signal generator 19 generates an electrical signal based on a command from the control device 17 and applies it to the AOD 11. The AOD 11 diffracts the pulsed laser beam Lb with a designated diffraction efficiency based on the applied electrical signal.

  In addition, the control device 17 issues a command for causing the trigger signal generator 18 to generate a trigger signal. The generated trigger signal is sent to the laser light source 10 and the pulsed laser beam Lb is emitted from the laser light source 10. At the time of emission of the pulse laser beam Lb, the AOD 11 is brought into a state (diffraction efficiency of 0%) in which the entire energy of the incident laser beam advances straight and enters the partial reflection mirror 12.

  With reference to FIG. 2 (A) and (B), the laser processing method performed using the laser processing apparatus by an Example is demonstrated. FIGS. 2A and 2B are diagrams for explaining laser processing methods according to the first and second embodiments, respectively.

  FIG. 2A shows an example of the relationship between the time after the trigger signal is input and the laser intensity of the pulse laser beam emitted from the laser light source 10.

At time 0, the trigger signal generated by the trigger signal generator 18 in response to an output command from the control device 17 is input to the laser light source 10. By inputting the trigger signal, the laser light source 10 starts emitting a pulse laser beam at time τ ₁ . The laser intensity of the pulse laser beam gradually increases and becomes substantially constant (I (τ ₃ )) at time τ ₃ . The laser intensity of the pulse laser beam decreases after time τ ₄ and becomes 0 at time τ ₅ .

For example, the time (τ ₃ ) at which the laser intensity becomes constant (steady state) and the constant intensity (I (τ ₃ )) are obtained from the pulse laser beam at time τ _{1 to} τ ₃ (transient state up to the steady state). There is a correlation with the rising condition, and it can be determined to some extent by the rising condition. If steep rise condition, the value of tau ₃ is small, the value of I (τ ₃₎ tends to increase. Further, if the gradual rise condition, the value of tau ₃ is large, the value of I (τ ₃₎ is tends to be small is observed.

On the other hand, when a pulsed laser beam having an inappropriately large or small laser intensity I (τ ₃ ) is incident on the processing region 16, it becomes difficult to perform processing with high processing quality.

Therefore, in the laser processing method according to the first embodiment, when the laser intensity I (τ ₃ ) is incident on the processing region 16 for the laser pulse emitted from the laser light source 10, the processing is performed with high processing quality. A criterion for determining whether or not the laser intensity is difficult is determined in advance by the laser intensity at time τ ₂ within the rising period (τ _{1 to} τ ₃ ) of the laser pulse. For example time tau laser intensity I (tau ₂₎ at _2, if the laser pulse is less than _{I min} or more _{I max,} be caused to enter the machining area 16 is capable of processing high quality _{I min} and _{I max} The value is obtained experimentally prior to machining and is stored in the storage device 17a of the control device 17.

Further, according to the laser intensity I (τ ₂ ) at the time τ ₂ , for example, for each value, the energy of each laser pulse incident on the processing region 16 is within an allowable range where processing is appropriately performed (for example, processing is optimal). The diffraction efficiency, such as a constant value performed in step (3), or the amplitude value of the AOD control signal for realizing the diffraction efficiency is experimentally obtained and stored in the storage device 17a of the control device 17. An example is shown in FIG. For example, τ ₂ is 10 μsec.

  A trigger signal generated by the trigger signal generator 18 in response to a command from the control device 17 is applied to the laser light source 10, and a laser pulse is emitted from the laser light source 10. The emitted laser pulse passes through the AOD 11, a part of which is reflected by the partial reflection mirror 12 and enters the detector 14, and the laser intensity is detected over time. The detected laser intensity data is transmitted to the control device 17.

  Based on the transmitted laser intensity data, the control device 17 obtains the relationship between the elapsed time from the trigger signal output time and the light intensity during the transient period until the light intensity reaches a steady state. The control device 17 can also calculate the relationship between the elapsed time from the rising point of the laser pulse and the light intensity.

  There is only a certain delay time difference from the trigger signal output to the rise of the laser pulse, so the relationship between the elapsed time from the trigger signal output time and the light intensity, the elapsed time from the rise time of the laser pulse and the light intensity It can be said that this relationship is equivalent. The control device 17 may directly obtain the relationship between the elapsed time from the rising point of the laser pulse and the light intensity from the transmitted laser intensity data.

Based on this relationship, the control device 17 determines whether or not the laser intensity I (τ ₂ ) at time τ ₂ is not less than I _{min and not} more than I _max .

When the laser intensity I (τ ₂ ) is greater than or equal to I _{min and} less than or equal to I _max , the controller 17 causes the AOD control signal generator 19 to generate a high-frequency electric signal after the light intensity of the laser pulse reaches a steady state. A command is issued, the laser pulse is deflected by the AOD 11 with the commanded diffraction efficiency, and is incident on the processing region 16. The diffraction efficiency of the AOD 11 is controlled for each laser pulse in accordance with the laser intensity I (τ ₂ ) so that the energy incident on the processing region 16 becomes an optimum constant value, for example. The AOD 11 may be operated, for example, 20 μsec after the rise time (time τ ₁ ) of the laser pulse.

When it is determined that the laser intensity I (τ ₂ ) at time τ ₂ is smaller than I _min and larger than I _max , the control device 17 causes the AOD 11 to deflect the laser pulse. Do not enter. For this reason, this laser pulse does not enter the processing region 16 (diffraction efficiency 0%), and, for example, substrate drilling is not performed by the laser pulse.

  With reference to FIG. 2 (B), the laser processing method by the 2nd Example is demonstrated.

In the laser processing method according to the second embodiment, it is difficult to perform processing with high processing quality when the laser intensity I (τ ₃ ) is incident on the processing region 16 for the laser pulse emitted from the laser light source 10. the criterion for determining whether the laser intensity, by the time the laser intensity is I _th, determined in advance. I _th is, for example, a laser intensity value about 1/2 of I (τ ₃ ).

For example, if the time t when the laser intensity becomes I _th (the time when the trigger signal is input to the laser light source 10 is 0) is a laser pulse that is t _min or more and t _max or less, the laser beam is made incident on the processing region 16. However, the values of t _min and t _max at which high quality processing is possible are obtained experimentally prior to processing and stored in the storage device 17a of the control device 17.

Further, according to the time t at which the laser intensity becomes I _th , for example, for each value, the energy of each laser pulse incident on the processing region 16 is within an allowable range in which processing is appropriately performed (for example, processing is performed optimally). A diffraction efficiency such as a constant value) or an amplitude value of an AOD control signal that realizes the diffraction efficiency is experimentally obtained and stored in the storage device 17a of the control device 17. An example is shown in FIG.

  A trigger signal generated by the trigger signal generator 18 in response to a command from the control device 17 is applied to the laser light source 10, and a laser pulse is emitted from the laser light source 10. The emitted laser pulse passes through the AOD 11, a part of which is reflected by the partial reflection mirror 12 and enters the detector 14, and the laser intensity is detected over time. The detected laser intensity data is transmitted to the control device 17.

The measurement at time t when the laser intensity becomes I _th can be performed, for example, by the following method. The control device 17 has a clock signal, commands the trigger signal generator 18 to generate a trigger signal at the rising timing of one clock of the clock signal, and the number of clocks from the command until the laser intensity becomes I _th. The time t is measured by counting.

If t is a value smaller than t _min , and if the laser intensity does not reach I _th even at time t _max , the control device 17 does not input a signal for deflecting the laser pulse to the AOD 11. Therefore, this laser pulse does not enter the processing region 16 and, for example, substrate drilling is not performed by the laser pulse.

When t is a value not less than t _{min and not} more than t _max , the control device 17 issues a high frequency electrical signal generation command to the AOD control signal generator 19 after the light intensity of the laser pulse reaches a steady state. The laser pulse is deflected by the AOD 11 with the commanded diffraction efficiency and is incident on the processing region 16. The diffraction efficiency of the AOD 11 is controlled for each laser pulse in accordance with the detected value of t so that the energy incident on the processing region 16 becomes an optimal constant value, for example. The AOD 11 may be operated, for example, 20 μsec after the rise time (time τ ₁ ) of the laser pulse.

In the laser processing method according to the first example, the laser pulse with the laser intensity I (τ ₂ ) at time τ ₂ exceeding I _max was not deflected by the AOD 11 and was not used for processing.

For I (τ ₂ ) exceeding I _max , the diffraction efficiency that makes the energy of each laser pulse incident on the processing region 16 constant, for example, for each value according to I (τ ₂ ), or diffraction thereof The amplitude value of the AOD control signal for realizing the efficiency may be obtained experimentally and stored in the storage device 17a of the control device 17.

Even if the laser pulse I (τ ₂ ) exceeds I _max , the controller 17 issues a high-frequency electrical signal generation command to the AOD control signal generator 19 and deflects the laser pulse with the commanded diffraction efficiency by the AOD 11. And enter the processing region 16.

In the laser processing method according to the second embodiment, when t is smaller than t _min , the control device 17 does not input a signal for deflecting the laser pulse to the AOD 11, For example, the substrate drilling process was not performed.

For t smaller than t _min , depending on the value of t, for example, for each value, diffraction efficiency that makes the energy of each laser pulse incident on the processing region 16 constant, or AOD control that realizes the diffraction efficiency The amplitude value of the signal may be obtained experimentally and stored in the storage device 17a of the control device 17.

Even if t is a laser pulse smaller than t _min , the control device 17 issues a command to generate a high-frequency electric signal to the AOD control signal generator 19, deflects the laser pulse with the commanded diffraction efficiency by the AOD 11, and processing region 16 is incident.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto.

  For example, the laser processing apparatus shown in FIG. 1 is a single-axis processing machine in which the beam deflection direction of the AOD 11 is a predetermined one direction, but two types of electrical signals having different frequencies are transmitted through the AOD control signal generator 19. By inputting to AOD11, as shown in FIG. 5, it can also be set as a biaxial processing machine.

  In this case, for example, the energy for each laser pulse incident on the machining area on one axis is made equal to each other, and the energy for each laser pulse incident on the machining area on the other axis is also made equal to each other.

  It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like can be made.

  It can be used for laser processing in general.

It is the schematic which shows the laser processing apparatus by an Example. (A), (B) is a figure for demonstrating the laser processing method by the 1st, 2nd Example, respectively. Is a graph showing an example of the relationship between I (τ ₂₎ and the diffraction efficiency. Light intensity is a graph showing an example of the relationship between time and the diffraction efficiency to be the I _th. It is the schematic which shows the laser processing apparatus by a modification.

Explanation of symbols

10 Laser light source 11 AOD
12 Partial reflection mirror 13 Beam block 14 Detector 15, 15a, 15b Folding mirror 16, 16a, 16b Processing area 17 Control device 17a Storage device 18 Trigger signal generator 19 AOD control signal generator Lb, Lba-Lbe Pulse laser beam

Claims (8)

A laser light source for emitting a pulsed laser beam;
When the emission efficiency is commanded from the outside, the laser beam having the energy of the commanded emission efficiency out of the energy of the incident laser beam is emitted along the first path, and the laser beam having the remaining energy is secondly emitted. A beam deflector that emits along the path of
A detector for detecting the light intensity of the laser beam emitted along the second path;
A first optical system for causing a laser beam emitted along the first path to enter a first processing region;
A signal indicating the light intensity detected by the detector is input, and the control device controls the laser light source and the beam deflector.
(A) the beam deflector directing all energy of the incident laser beam to the second path and emitting a laser pulse from the laser light source;
(B) obtaining a relationship between the light intensity and the elapsed time from the rising point of the laser pulse during the transient period until the light intensity reaches a steady state;
(C) executing the step of determining the emission efficiency based on the acquired relationship and instructing the beam deflector on the determined emission efficiency after the light intensity of the laser pulse has reached a steady state. Laser processing equipment.   2. The laser processing apparatus according to claim 1, wherein in the step (c), the control device determines the emission efficiency so that a pulse energy of a laser pulse directed to the first path falls within an allowable range.   In the step (b), the control device acquires the light intensity after the elapse of the determination time from the rise of the laser pulse, and in the step (c), based on the light intensity acquired in the step (b). The laser processing apparatus according to claim 1, wherein the emission efficiency is determined.   The control device includes a storage unit that stores an allowable lower limit value of the light intensity after the determination time has elapsed. In the step (c), the light intensity acquired in the step (b) is less than the allowable lower limit value. The laser processing apparatus according to claim 3, wherein in some cases, the emission efficiency is set to 0%.   In the step (b), the control device acquires an elapsed time from the rise until the light intensity of the laser pulse reaches the determination reference strength. In the step (c), the control device acquired in the step (b). The laser processing apparatus according to claim 1, wherein the emission efficiency is determined based on an elapsed time.   The control device includes storage means for storing an allowable upper limit value of the elapsed time until the light intensity of the laser pulse reaches the determination reference intensity, and the elapsed time acquired in the step (b) in the step (c). The laser processing apparatus according to claim 5, wherein when the value exceeds the allowable upper limit, the emission efficiency is set to 0%. The control device instructs the beam deflector as a third path different from the first and second paths, or the first path as an output path,
When the emission efficiency and the emission path are commanded from the control device, the beam deflector emits a laser beam having an energy equivalent to the commanded emission efficiency along the commanded emission path. Emitting a laser beam of the remaining energy along the second path,
Further, the beam deflector causes the laser beam emitted along the third path to be incident on a second processing region different from the first processing region. The laser processing apparatus according to claim 1, comprising two optical systems. (A) a step of directing all the energy of the laser beam incident by the beam deflector to the first path, emitting a laser pulse from the laser light source, and entering the beam deflector;
(B) obtaining a relationship between the elapsed time from the rising point of the laser pulse and the light intensity during a transient period until the light intensity reaches a steady state;
(C) determining the emission efficiency based on the acquired relationship, and after the light intensity of the laser pulse has reached a steady state, the beam deflector is supplied with a laser beam having an energy equivalent to the determined emission efficiency; And a step of emitting a laser beam of the remaining energy along the first route, the step being emitted along a second route different from the first route.

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