JP5002250B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus using ultrashort pulse laser light.

2. Description of the Related Art Conventionally, as a method for changing laser power in a laser processing apparatus, one that changes the pulse peak value of pulsed laser light is known (for example, Patent Documents 1 and 2). This method is to increase the energy per pulse and ensure the necessary laser power by increasing the pulse peak value of the pulsed laser light as the required laser power increases. In this case, it is only necessary to irradiate one pulse laser beam at a predetermined processing point, so that a suitable processing rate (processing time) is maintained.
JP-A-8-321651 Japanese Patent No. 3411852

  By the way, when the pulse peak value of the pulse laser beam exceeds a certain value determined according to the material of the workpiece, the optical light absorption rate of the pulse laser beam by the workpiece is increased with respect to the increase amount of the pulse peak value. It is known that the amount can be reduced.

  That is, FIG. 5 shows the relationship between the pulse energy and the optical absorbance (Absorbance) correlated with the pulse peak value for a plurality of types (four types) of materials M1, M2, M3, and M4. As shown in the graph, when the pulse energy is small, it is confirmed that the light absorption rate increases as the pulse energy increases. Further, when the pulse energy exceeds a certain value for each of the materials M1 to M4 (illustrated by an arrow ↓), it is confirmed that an increase in light absorption rate with respect to an increase in pulse energy is suppressed. Here, it is confirmed that when the pulse energy exceeds a certain value for each of the materials M1 to M4, the increase in the light absorption rate according to the increase in the pulse energy is suppressed at the light absorption rate corresponding to the certain value. The

  That is, in such a state, even if the pulse peak value (pulse energy) is increased in order to increase the laser power, the ratio of the pulsed laser light that is not used for processing is increased, and the pulsed laser light The light utilization efficiency is deteriorated.

  An object of the present invention is to perform laser processing with high light utilization efficiency of pulsed laser light by adjusting laser power over a wide range without reducing the processing rate as much as possible in a laser processing apparatus using short pulsed laser light. An object of the present invention is to provide a laser processing apparatus that can perform the above processing.

In order to solve the above problems, the invention described in claim 1 is directed to a laser light source that emits a short pulse laser beam, and a pulse laser beam emitted from the laser light source is converged and irradiated on a workpiece. A converging lens, laser power setting means for setting the set value of the laser power of the pulsed laser light irradiated to the object to be processed based on an external signal, and laser power set by the laser power setting means A pulse condition setting means for setting a pulse condition of the pulse laser light of the laser light source based on the set value of the laser light source; and a control means for controlling the laser light source based on the pulse condition set by the pulse condition setting means; wherein the pulse condition setting means, the set value of the laser power set by the laser power setting means, a predetermined reference laser power The pulse condition is changed by the pulse peak value of the pulsed laser beam, and when higher than the reference laser power, the pulse condition is changed by the number of pulses per predetermined period of the pulsed laser beam. The gist is to make it.

  According to each of the above configurations, the set value of the laser power of the pulsed laser light set by the laser power setting means is such that the optical value of the pulsed laser light by the object to be processed with respect to the increase amount of the pulse peak value of the pulsed laser light. When the amount of increase in the light absorption rate is higher than a predetermined laser power (reference laser power) that can be suppressed, the pulse condition is changed by the number of pulses per predetermined period of the pulse laser light by the pulse condition setting means. As a result, it is possible to suppress a decrease in the light utilization efficiency of the pulsed laser light while adjusting the laser power over a wide range.

  On the other hand, when the set value of the laser power of the pulse laser beam set by the laser power setting means is lower than the predetermined laser power (reference laser power), the pulse condition is set by the pulse condition setting means. By changing according to the pulse peak value of the pulse laser light, for example, there is no need to irradiate a predetermined processing point with a plurality of pulse laser lights as in the case where the pulse laser light is changed according to the number of pulses per predetermined period. , The reduction of the processing rate can be suppressed.

Invention according to claim 2, in the laser processing apparatus according to claim 1, wherein when the pulse condition setting means sets the pulse conditions by the number of pulses for each predetermined period of the pulsed laser light, the pulse The gist is to set it by the repetition frequency of the laser beam.

  According to this configuration, when a plurality of pulse laser beams are irradiated to a predetermined processing point in order to satisfy the necessary laser power of the pulse laser beam irradiated to the workpiece, the repetition frequency of the pulse laser beam is set. By changing the corresponding cycle to be shorter, useless waiting time that occurs in the cycle corresponding to the original repetition frequency can be eliminated, and the processing rate can be increased.

According to a third aspect of the present invention, in the laser processing apparatus according to the first or second aspect , a plurality of types of materials of the workpiece, a set value of the laser power for each material, and a set value of the laser power Storage means for storing pulse conditions, and selection means for selecting any one of the plurality of types of materials, wherein the pulse condition setting means is configured to select any one of the plurality of types of materials by the selection means. And selecting a pulse condition stored in the storage unit for the set value of the laser power based on the set value of the laser power set by the laser power setting unit. To do.

  According to the same configuration, one of a plurality of types of materials stored in advance of the workpiece is selected, and based on a laser power setting value set by the laser power setting unit. The pulse condition stored in the storage means is set with respect to the set value of the laser power, and can be adjusted to the optimum laser power, and the setting (change) of the pulse condition can be simplified.

According to a fourth aspect of the present invention, in the laser processing apparatus according to the first or second aspect , the light receiving means for receiving the light that is reflected or transmitted through the processing object by the pulsed laser light applied to the processing object. And detecting the received light amount received by the light receiving means while sequentially changing the laser power by the laser power setting means, and based on the detected received light amount for each set value of the laser power, And a reference laser power setting means for setting the set value of the laser power when the change of the laser beam is below a predetermined increase amount to the reference laser power.

  According to this configuration, even when laser processing is performed on an enormous variety of materials of the processing object, the reference laser power is set by the teaching mode, so that the material processed by the user can be flexibly set. Can respond.

The gist of the invention according to claim 5 is the laser processing apparatus according to any one of claims 1 to 4 , wherein the pulse laser beam is a short pulse laser beam of picosecond order or less. .

  According to this configuration, in the laser processing technology field where processing that does not generate heat (so-called cold machining) is possible, pulse laser light is absorbed and used for processing, or pulse laser light is not absorbed and used for processing. As a result, the change in the optical absorption rate of the pulsed laser beam due to the workpiece can be more clearly manifested, thereby reducing the light utilization efficiency of the pulsed laser beam. Can be more suitably suppressed.

A sixth aspect of the present invention is the laser processing apparatus according to any one of the first to fifth aspects, wherein the processing object is irradiated with the pulsed laser light that is scanned with the pulsed laser light from the laser light source. Optical scanning means for scanning
The gist of the invention is that the control means changes the scanning speed of the optical scanning means in accordance with the number of pulses of the pulsed laser light for each predetermined period set by the pulse condition setting means.

  According to this configuration, when the pulse laser beam and the object to be processed are relatively moved, for example, the pulse laser beam from the laser light source is moved rather than moving the table for processing or the head that irradiates the object to be processed with the pulse laser beam. Since the scanning is faster, the processing rate can be further increased.

In the invention described in each claim, in a laser processing apparatus using a short pulse laser beam, the laser power is adjusted in a wide range without reducing the processing rate as much as possible, and a laser with high light use efficiency of the pulse laser beam A laser processing apparatus capable of performing processing can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 shows a configuration block diagram of a laser processing apparatus 10 of the present embodiment. The laser processing apparatus 10 is for marking characters, symbols, figures, etc. on the surface of the workpiece W, for example.

  A laser light source 11 of the laser processing apparatus 10 is composed of a laser oscillator (for example, a YAG laser), emits an ultrashort pulse laser light L for processing, and is electrically controlled by a control means 12b of a controller 12 connected thereto. Oscillation is controlled. The set value of the laser power of the pulsed laser beam L is set to be changeable by the laser power setting unit 12c of the controller 12, and the pulse condition of the pulsed laser beam L is set by the laser power setting unit 12c. Based on the set value of the laser power, it is set by the pulse condition setting means 12d of the controller 12. The control means 12b controls the laser light source 11 based on the pulse condition set by the pulse condition setting means 12d. In the present embodiment, the laser light source 11 emits, as the pulsed laser beam L, a short pulsed laser beam with a pulse width (pulse duty) equal to or less than a picosecond order. Then, the pulse condition setting means 12d of the controller 12 sets the pulse peak value and the repetition frequency (cycle) of the pulse laser light L as the pulse condition.

  Based on this pulse condition, the control means 12b of the controller 12 controls the drive current for the laser light source 11 to change and control the pulse peak value of the pulsed laser light L. The controller 12b of the controller 12 controls the supply timing of the drive current to the laser light source 11, and changes / controls the repetition frequency corresponding to the number of pulses of the pulsed laser light L for each predetermined period.

  An optical scanning mechanism 13 serving as an optical scanning unit disposed at the subsequent stage of the laser light source 11 is constituted by, for example, a galvano mirror including a pair of X-axis mirror and Y-axis mirror, and a pulse emitted from the laser light source 11. The laser beam L is reflected and the irradiation direction is changed. In the optical scanning mechanism 13, the rotation angle of each mirror is controlled by the control means 12b of the controller 12 electrically connected. By rotating each mirror, the pulse laser beam L is two-dimensionally scanned based on the characters, symbols, figures, etc. to be marked. The control of each mirror by the control means 12b of the controller 12, that is, the scanning speed of the pulse laser beam L is controlled in accordance with the repetition frequency of the pulse laser beam L.

  A converging lens (fθ lens) 14 disposed downstream of the optical scanning mechanism 13 condenses the pulsed laser light L whose irradiation direction has been changed by the optical scanning mechanism 13. The surface of the workpiece W is marked by the pulse laser beam L.

  The operation unit 15 serving as a selection unit electrically connected to the laser power setting unit 12c of the controller 12 is used to process the workpiece W (for example, information on characters, symbols, figures, etc. to be marked, The material is operated by the user to select and set the material and the laser power of the pulse laser beam L irradiated to one processing point, and the set processing information is output to the controller 12 as an external signal.

  The laser power setting means 12c of the controller 12 sets the laser power of the pulsed laser light L irradiated to the workpiece W based on an external signal from the operation unit 15 so as to be changeable. Specifically, the controller 12 stores a plurality of types of materials of the workpiece, a set value of the laser power for each material, and a pulse condition for the set value of the laser power in a memory 12a serving as a storage unit therein. Pre-stored. Then, the laser power setting means 12c of the controller 12 acquires processing information on the material of the workpiece W and the laser power of the pulsed laser light L based on an external signal from the operation unit 15, and is stored in advance in the memory 12a. The pulse conditions (pulse peak value and repetition frequency) corresponding to the machining information are selected and set from the pulse conditions. Then, the controller 12b of the controller 12 supplies a drive current corresponding to the set pulse peak value to the laser light source 11 at a timing corresponding to the set repetition frequency. At the same time, the control means 12b of the controller 12 drives the optical scanning mechanism 13 in accordance with the set repetition frequency.

  In the laser processing apparatus 10 configured as described above, when marking the workpiece W, the control means 12b of the controller 12 uses a laser light source according to the aforementioned pulse conditions (pulse peak value and repetition frequency). 11 is driven to emit pulsed laser light L. Further, the control means 12b of the controller 12 drives the optical scanning mechanism 13 in accordance with the processing information output from the operation unit 15, scans the pulsed laser light L emitted from the laser light source 11 two-dimensionally, and processes the workpiece W. A predetermined shape of marking is performed on the surface of the substrate.

  Here, the relationship between the laser power setting value set by the user's operation and the pulse condition stored in advance in the memory 12a corresponding to the laser power setting value will be described.

  2 (a) and 2 (b), regarding a certain material of the workpiece W, the laser power setting value P set by the user's operation and the memory 12a corresponding to the laser power setting value P are stored in advance. It is a map which shows the relationship between the pulse peak value A and the repetition frequency f as a pulse condition currently performed.

  As shown in the figure, when the laser power set value P is less than or equal to a predetermined reference laser power Px, the pulse peak value A of the pulsed laser light L increases as the laser power set value P increases. In addition, the pulse condition is set so that the repetition frequency f is maintained at a predetermined repetition frequency f0. On the other hand, when the laser power set value P exceeds the reference laser power Px, the pulse peak value A of the pulsed laser light L is held at a predetermined pulse peak value A0 and the laser power set value P is set. The pulse condition is set so that the repetition frequency f increases with the increase of. The reference laser power Px, the pulse peak value A0, and the repetition frequency f0 are constant values determined in advance for each material of the workpiece W. For example, the reference laser power Px is a laser unique to each material that can suppress an increase in the optical light absorptance of the pulse laser beam L by the workpiece W with respect to an increase in the pulse peak value of the pulse laser beam L. Power.

  Accordingly, when the laser power set value P is less than or equal to the reference laser power Px, the laser light source 11 that is driven and controlled by the controller 12 has one pulse peak value A that increases as the laser power set value P increases. The laser beam L is irradiated to a predetermined processing point, and the irradiation direction is changed to the next processing point by the optical scanning mechanism 13 in accordance with the repetition frequency f0. In this way, since it is only necessary to irradiate one pulsed laser beam L at a predetermined processing point, a suitable processing rate is maintained while ensuring the necessary laser power.

  On the other hand, when the set value P of the laser power exceeds the reference laser power Px, the laser light source 11 that is driven and controlled by the controller 12 pulses in accordance with the repetition frequency f that increases as the set value P of the laser power increases. A plurality of (two) pulse laser beams L having a peak value A0 are sequentially irradiated onto a predetermined processing point, and the irradiation direction is next adjusted to a frequency (f / 2) half of the repetition frequency f by the optical scanning mechanism 13. The machining point is changed. In this way, the necessary laser power is ensured by irradiating the predetermined processing point with the pulsed laser beam L having a plurality of pulses. As described above, the laser power can be adjusted over a wide range without lowering the light utilization efficiency of the pulsed laser light L.

  In addition, although the reduction of a processing rate is assumed by irradiating a predetermined | prescribed processing point with the pulsed laser beam L of a several pulse, the fall of a processing rate is suppressed by coping with the increase in the repetition frequency f.

  FIG. 3A shows a reference state in which only one pulsed laser beam L is irradiated to a predetermined processing point, and the pulsed laser beam L is irradiated every period T corresponding to the repetition frequency f0. It is explanatory drawing shown. 3B and 3C show a case where two pulsed laser beams L are irradiated to a predetermined processing point, and the number of pulses of the pulsed laser beam L irradiated at each period T is two. FIG. 6 is an explanatory diagram showing a state in which the pulse laser light L is irradiated every time (T / 2) half of the period T (a state in which the repetition frequency f is doubled). .

  As shown in FIG. 3B, when irradiating a predetermined processing point with two pulsed laser beams L for each period T, how much the irradiation interval of the two pulsed laser beams L is reduced. However, the change of the irradiation direction to the next processing point is performed after the elapse of the period T, resulting in a wasteful waiting time.

  On the other hand, as shown in FIG. 3 (c), even when one pulsed laser beam L is irradiated to a predetermined processing point every half time (T / 2) of the period T, every period T Two pulsed laser beams L are irradiated. In other words, if one pulsed laser beam L is irradiated to a predetermined processing point every time shorter than the time (T / 2), that is, if the repetition frequency f is made larger than twice, the repetition frequency As f is increased, the irradiation direction to the next processing point can be changed in a shorter time with respect to the period T.

  As described above, in the case of irradiating the predetermined laser beam with a plurality of pulses of laser light L, a decrease in the processing rate is suppressed as compared with the case where the number of pulses of the pulse laser light L for each period T is increased.

As described above in detail, according to the present embodiment, the following effects can be obtained.
(1) In the present embodiment, when the set value P of the laser power of the set pulse laser light L is higher than the reference laser power Px, the controller 12 sets the pulse condition of the pulse laser light L. By changing according to the repetition frequency, it is possible to suppress a decrease in light utilization efficiency of the pulsed laser light L while adjusting the laser power over a wide range.

  On the other hand, when the set value P of the laser power of the set pulse laser beam L is lower than the reference laser power Px, the controller 12 changes the pulse condition according to the pulse peak value of the pulse laser beam L. By irradiating a predetermined processing point with a plurality of pulses of laser light L, for example, when changing according to the repetition frequency of the pulse laser light L or the number of pulses of the pulse laser light L per predetermined period Therefore, it is possible to suppress a reduction in the processing rate.

  (2) In the present embodiment, a predetermined processing point is irradiated with a plurality of pulses of pulsed laser light L so as to satisfy a necessary laser power setting value P of the pulsed laser light L irradiated onto the workpiece W. In this case, by changing the period corresponding to the repetition frequency of the pulsed laser light L to be shorter, it is possible to eliminate the wasteful waiting time that occurs in the period corresponding to the original repetition frequency, and to increase the processing rate. Can do.

In particular, when scanning a plurality of machining points, it is possible to quickly move from one machining point to the next machining point, and the machining rate can be increased as a whole.
(3) In the present embodiment, any one of a plurality of pre-stored materials of the workpiece W is selected through the operation unit 15 and is set by the laser power setting means. Based on the set value of the laser power, the pulse condition stored in the memory 12a is set for the set value of the laser power, and can be adjusted to the optimum laser power. It can be simplified.

  (4) In the present embodiment, the pulsed laser light is absorbed in the laser processing technology field capable of non-heat generation processing (cold machining) because the pulsed laser light L is a short light pulse laser light of picosecond order or less. Therefore, the state of being used for processing or the state of not being used for processing because the pulse laser beam is not absorbed appears more prominently. This can be clearly manifested, whereby the reduction in the light utilization efficiency of the pulsed laser light L can be more suitably suppressed.

  (5) In this embodiment, the pulse laser beam L from the laser light source 11 is scanned by the optical scanning mechanism 13 to move the pulse laser beam L and the workpiece W relative to each other. Compared with moving the head that irradiates the workpiece W with the pulse laser beam L, the processing can be performed at a higher speed, and the processing rate can be further increased.

  (6) In general, when the energy per pulse is changed by increasing or decreasing the pulse width of the pulse laser beam in order to vary the laser power, the light converted into heat in addition to the light used for processing at the processing point Since the ratio increases or decreases, the processing state at the processing point may change significantly. In particular, in the processing technical field called non-heat generation processing (cold machining) such as processing using an ultrashort pulse laser beam, generation of heat is not preferable. In this embodiment, regardless of the set value P of the laser power, the change in the machining state at the machining point can be suppressed because the pulse width of the pulsed laser light L is constant.

In addition, you may change the said embodiment as follows.
As shown in FIG. 4, the pulse laser beam L applied to the workpiece W is detected by the optical measuring device 21 as a light receiving unit electrically connected to the reference laser power setting unit 12 e of the controller 12. While receiving the light which permeate | transmitted the workpiece W, you may make it output the signal according to the received light quantity to the controller 12 as an external signal. In this case, the laser power setting means 12c of the controller 12 detects the received light amount received by the optical measuring device 21 while increasing the set value of the laser power, and the detected received light amount for each set value of the laser power. Based on the above, the set value of the laser power when the change in the amount of received light with respect to the increase amount of the laser power falls below a predetermined increase amount is set as the reference laser power Px. The reference laser power Px may be set in a teaching mode mounted on the controller 12 separately from the normal processing mode.

  By changing in this way, in addition to the same effects as (1), (2), (4) to (6) of the above-described embodiment, it is a case where laser processing is performed on a huge variety of materials of the workpiece W. However, by setting the reference laser power Px by the reference laser power setting unit 12e, it is possible to flexibly cope with the material processed by the user. That is, the controller 12 does not need to store a plurality of types of materials of the workpiece W in the memory 12a in advance, and may set the pulse condition based on the reference laser power Px set in the above-described manner. . Note that, as indicated by a broken line in FIG. 4, the light measuring device 21 receives the light reflected by the processing object W by the pulsed laser light L applied to the processing object W. May be.

  In the embodiment, when the set value P of the laser power exceeds the reference laser power Px, the pulse peak values A of the two pulses of the pulse laser light L are equal to each other according to the set value P of the laser power. The pulse condition may be set so that the pulse peak value is obtained. Alternatively, the pulse peak value A of the first pulse of the pulsed laser light L is held at a predetermined pulse peak value A0, and the pulse peak value A of the second pulse is set to the laser power set value P. The pulse condition may be set so as to obtain a predetermined pulse peak value according to the above.

In the embodiment, the pulse energy may be adjusted by finely adjusting the pulse width in accordance with the change of the pulse peak value A.
In the embodiment, when the set value P of the laser power exceeds the reference laser power Px, the pulse condition may be changed according to the number of pulses per predetermined period (period T) of the pulsed laser light L.

  In the above embodiment, the laser light source 11 is composed of, for example, a plurality of semiconductor lasers, and the controller 12 changes the number of semiconductor lasers to be driven, thereby changing the pulse peak value A of the pulsed laser light L. Also good.

The block diagram which shows one Embodiment of this invention. (A) (b) is a map which shows the relationship between a laser power, a pulse peak value, and a repetition frequency, respectively. (A) (b) (c) is explanatory drawing which shows operation | movement of the embodiment. The block diagram which shows the modification of this invention. The graph which shows the relationship between pulse energy and a light absorption rate.

Explanation of symbols

  W ... object to be processed, 10 ... laser processing device, 11 ... laser light source, 12 ... controller, 12a ... memory (storage means), 12b ... control means, 12c ... laser power setting means, 12d ... pulse condition setting means, 12e ... Reference laser power setting means, 13 ... optical scanning mechanism (optical scanning means), 14 ... converging lens, 15 ... operation unit, 21 ... optical measuring device (light receiving means).

Claims (6)

A laser light source that emits a short pulse laser beam;
A converging lens that converges and irradiates the object to be processed with the pulsed laser light emitted from the laser light source;
Laser power setting means for setting the set value of the laser power of the pulsed laser light irradiated to the object to be processed based on an external signal to be changeable;
Pulse condition setting means for setting a pulse condition of the pulse laser beam of the laser light source based on a set value of the laser power set by the laser power setting means;
Control means for controlling the laser light source based on the pulse condition set by the pulse condition setting means,
The pulse condition setting means includes
When the set value of the laser power set by the laser power setting means is lower than a predetermined reference laser power, the pulse condition is changed by the pulse peak value of the pulse laser light,
When the reference laser power is higher than the reference laser power , the laser processing apparatus is characterized in that the pulse condition is changed by the number of pulses per predetermined period of the pulse laser light . In the laser processing apparatus of Claim 1 ,
The laser processing apparatus, wherein the pulse condition setting means sets the pulse condition based on the repetition frequency of the pulse laser beam when setting the pulse condition based on the number of pulses per predetermined period of the pulse laser beam. In the laser processing apparatus according to claim 1 or 2 ,
Storage means for storing a plurality of types of materials of the workpiece, a set value of the laser power for each material, and a pulse condition for the set value of the laser power;
Selecting means for selecting any one of the plurality of types of materials;
With
The pulse condition setting means includes
Based on the set value of the laser power set by the laser power setting means by selecting any one of the plurality of kinds of materials by the selecting means, the storage means for the set value of the laser power A laser processing apparatus characterized in that a pulse condition stored in the is set. In the laser processing apparatus according to claim 1 or 2 ,
A light receiving means for receiving the light reflected or transmitted by the pulsed laser light applied to the object to be processed;
While the laser power is sequentially changed by the laser power setting means, the received light amount received by the light receiving means is detected, and the change in the received light amount is determined based on the detected received light amount for each set value of the laser power. A laser processing apparatus, comprising: a reference laser power setting unit that sets a set value of the laser power when the value is less than a predetermined increase amount to the reference laser power. In the laser processing apparatus as described in any one of Claims 1-4 ,
The laser processing apparatus, wherein the pulse laser beam is a short pulse laser beam of picosecond order or less. In the laser processing apparatus as described in any one of Claims 1-5 ,
An optical scanning unit that scans pulse laser light from the laser light source and scans pulse laser light applied to the workpiece;
The laser processing apparatus characterized in that the control means changes the scanning speed of the optical scanning means in accordance with the number of pulses of the pulsed laser light for each predetermined period set by the pulse condition setting means.

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