JP2007245159A - 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 for machining a workpiece highly precisely with laser beams wparticularly. <P>SOLUTION: The laser beam machining apparatus includes: a laser oscillator 21 for emitting a pulsed laser beam of a prescribed output; a trigger pulse generator 30 for outputting a trigger signal to the laser oscillator; an optical modulator 25 for adjusting a pulse width per shot; and an energy monitor 28 for detecting pulsed energy per shot. Additionally, the apparatus is equipped with an energy comparator 29 which is capable of setting a pulsed energy in accordance with machining conditions for a workpiece and setting a threshold value for the pulsed energy, which makes a comparison between the set threshold value and the pulsed energy detected by the energy monitor and which, when the pulsed energy is the threshold value or below, sends a signal to the trigger pulse generator and the optical modulator so that the pulsed energy in short supply is outputted to the workpiece. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus and a laser processing method, and more particularly to a laser processing apparatus and a laser processing method for realizing highly accurate laser processing on a processing target.

  2. Description of the Related Art Conventionally, there is a technique for performing laser processing by irradiating a processing object such as a printed wiring board with one or a plurality of laser beams using a pulse laser generated from a laser oscillator. Here, in a laser processing apparatus using a laser oscillator, there may occur a phenomenon such as energy loss or misfire (empty shot) that occurs in the optical path after emission from the laser oscillator. In such a case, the energy of the laser beam at the processing point is small or the number of shots is insufficient, resulting in processing failure.

  Therefore, conventionally, there is a laser processing apparatus that can monitor the pulse energy for each pulsed laser beam emitted from the laser oscillator, and can compensate for this when the pulse energy decreases (see, for example, Patent Document 1). .

FIG. 1 is a diagram for explaining how laser light is compensated in a conventional laser processing apparatus. In conventional laser processing equipment, the pulse energy emitted from the laser oscillator is detected, and if it is below a preset threshold value (threshold value), additional shots are automatically made to compensate for this, and holes such as resin residues are drilled. Prevent defects. For example, when performing processing of one processing point, if pulse laser light for three shots is necessary, as shown in FIG. 1, the third shot is equal to or less than a preset threshold value, so that the additional shot is the same processing point. Is irradiated and processed.
Japanese Patent No. 2858236

  However, in the prior art, for example, when the pulse laser beam related to a certain shot has an energy loss slightly less than the threshold value, an additional shot is emitted once. In this case, processing at one processing point is performed. There is a risk that the pulse energy is excessive than the pulse energy necessary for the above.

  FIG. 2 is a diagram illustrating an example of a conventional drilling shape. The processing object 10 shown in FIG. 2 has a layer 12 to be processed such as a resin having metal films 11-1 and 11-2 such as copper foil on both surfaces, and one surface (for example, an opening of the metal film 11-1). The processing layer 12 is processed by irradiating the surface) with laser light. For example, a copper wiring pattern or the like is formed on the metal film 11-2.

  Here, FIG. 2A shows the processing state of the processing object when the number of shots of the pulsed laser light irradiated to the processing point is all OK (greater than the threshold value), and FIG. Indicates at least one of the pulsed laser beams irradiated to the processing point is NG (slightly below the threshold), and indicates the processing state of the processing object when an additional shot is performed.

  As shown in FIG. 2A, when the process is completed normally, the processing is performed without remaining resin. In addition, when an additional shot is irradiated, a fatal defect such as disconnection due to a resin residue can be prevented. However, depending on the type of substrate and processing conditions, as shown in FIG. 2 (b), the inner wall becomes a barrel shape of Dn> Dt, damage to the metal film 11-2, etc. occurs, resulting in a decrease in processing quality. There is a risk of inviting.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a laser processing apparatus and a laser processing method for realizing high-precision laser processing on a workpiece.

  In order to achieve the above-described object, the present invention emits a pulse laser beam having a set output value in a laser processing apparatus that performs processing by irradiating a workpiece with a pulse laser beam of a predetermined pulse energy. A laser oscillator, a trigger pulse generation unit that outputs a trigger signal to the laser oscillator, and an optical path that guides the pulse laser beam from the laser oscillator to the workpiece, to adjust the pulse width for each shot An optical modulator, an energy monitor for detecting pulse energy for each shot, and the pulse energy and a threshold value for the pulse energy can be set according to the processing conditions for the processing object. Comparing the set threshold value with the pulse energy detected by the energy monitor, When the pulse energy is equal to or less than the threshold value, the trigger pulse generation unit and the energy comparison unit that outputs a signal for outputting the insufficient pulse energy to the workpiece are output to the optical modulator. It is characterized by that. Thereby, the highly accurate laser processing to a process target object is realizable.

  Furthermore, it is preferable that the energy comparison unit calculates the insufficient pulse energy from difference information between the pulse energy obtained by the energy monitor and the predetermined pulse energy. Thereby, since excess energy is not given to a workpiece, quality stabilization can be achieved.

  Furthermore, the energy comparison unit outputs a signal for emitting an additional pulse laser beam to the trigger pulse generation unit, and the optical modulator causes the shortage of the pulse energy to be applied to the workpiece. It is preferable to adjust the pulse width of the pulse laser beam emitted from the laser oscillator. Thereby, the pulse energy can be adjusted quickly and accurately by controlling the pulse width.

  Furthermore, it has a peak output control unit that controls a peak output value of the laser oscillator, and the energy comparison unit is emitted by the laser oscillator so that the insufficient pulse energy is irradiated to the workpiece. It is preferable to output a control signal for adjusting the peak output value of the pulsed laser beam to the peak output control unit. Thus, the pulse energy can be adjusted quickly and accurately by controlling the peak output value of the pulse.

  Further, the present invention provides a trigger pulse generation step of outputting a trigger signal from a trigger pulse generator to a laser oscillator in a laser processing method for performing processing by irradiating a processing target with pulse laser light of a predetermined pulse energy, An emission stage for emitting a pulse laser beam having a peak output value set by the trigger signal from the laser oscillator, and an optical modulator provided in an optical path for guiding the pulse laser beam from the laser oscillator to the workpiece A pulse width adjusting step for adjusting the pulse width for each shot, a detecting step for detecting the pulse energy for each shot by an energy monitor, and the pulse energy and the pulse energy according to the processing conditions for the processing object. Threshold value can be set and set threshold hole When the pulse energy is compared with the pulse energy detected by the energy monitor and the pulse energy is equal to or less than the threshold value, a signal for causing the workpiece to output insufficient pulse energy is the trigger pulse. And an energy comparison step of outputting to the optical modulator. Thereby, the highly accurate laser processing to a process target object is realizable.

  Furthermore, it is preferable that the energy comparison step calculates a shortage of pulse energy from difference information between the pulse energy obtained by the energy monitor and the predetermined pulse energy. Thereby, since excess energy is not given to a workpiece, quality stabilization can be achieved.

  Furthermore, it is preferable to adjust the pulse width of the pulse laser beam emitted from the laser oscillator by the optical modulator so that the insufficient amount of pulse energy is applied to the workpiece. Thereby, the pulse energy can be adjusted quickly and accurately by controlling the pulse width.

  Furthermore, it is preferable to adjust the peak output value of the pulsed laser beam emitted by the laser oscillator so that the machining target object is irradiated with the insufficient pulse energy. Thus, the pulse energy can be adjusted quickly and accurately by controlling the peak output value of the pulse.

  ADVANTAGE OF THE INVENTION According to this invention, the highly accurate laser processing to a process target object is realizable.

  Hereinafter, preferred embodiments of a laser processing apparatus and a laser processing method according to the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 3 is a diagram illustrating an example of a schematic configuration of the laser processing apparatus according to the first embodiment. FIG. 4 is a diagram illustrating an example of a timing chart during processing. 3 includes a laser oscillator 21, bending mirrors 22, 23, 24, an optical modulator 25, a half mirror 26, a processing lens 27, an energy monitor 28, and an energy comparison circuit (energy comparison circuit). (Comparator) 29, trigger pulse generator circuit (trigger pulse generator) 30, and beam damper 31.

The laser oscillator 21 emits a pulse laser beam as shown in FIG. 4B based on a trigger signal from the trigger pulse generation circuit 30 as shown in FIG. As the laser light output from the laser oscillator 21, laser light used for laser processing such as CO ₂ laser, YAG laser, excimer laser, fundamental wave and harmonic solid laser can be used.

  The bending mirrors 22 and 23 guide the pulsed laser light emitted from the laser oscillator 21 in a preset direction. The bending mirror 24 guides the pulsed laser light from the optical modulator 25 in a preset direction.

  Further, the optical modulator 25 as a traveling direction control element controls the deflection of the laser beam based on the pulse deflection signal from the energy comparison circuit 29 as shown in FIG. 4C, and branches the incident pulse laser. Let

  One of the branched laser beams is output to the half mirror 26 as a processing pulse shaped as shown in FIG. 4D, and the other is output to the beam damper 31. That is, by adjusting the ON / OFF time (T in FIG. 4) in the pulse deflection signal, the energy of the pulse laser beam outputted to the half mirror 26 is adjusted by branching the pulse laser beam for a predetermined time by the optical modulator 25. can do.

  The optical modulator 25 may be, for example, an AOM (Acoustic Optical Modulator) or an EOM (Electro Optical Modulator).

  The half mirror 26 transmits a predetermined ratio (for example, about 99%) of the pulsed laser light, and reflects the remaining ratio (for example, about 1%) of the pulsed laser light. .

  The laser beam that has passed through the half mirror 26 is condensed to a predetermined beam diameter by the processing lens 27 and irradiated onto the workpiece 10 to be processed. The processing object 10 is fixed on, for example, an XY stage (not shown), and the XY stage moves in the horizontal direction or the like, thereby realizing laser processing on a predetermined processing point of the processing object 10. Can do.

  The energy monitor 28 receives the pulse laser beam reflected from the half mirror 26 and detects the pulse energy for each pulse. The energy monitor 28 outputs the detected pulse energy to the energy comparison circuit 29.

  The energy comparison circuit 29 compares the pulse energy obtained by the energy monitor 28 with a preset threshold value. Further, the energy comparison circuit 29 outputs an emission instruction signal for additional shots to the trigger pulse generation circuit 30 when additional pulse laser light is necessary based on the comparison result.

  Further, the energy comparison circuit 29 calculates the shortage from the difference information between the pulse energy obtained by the energy monitor 28 and the preset pulse energy (pulse energy setting value) when additional pulse laser light is required. The pulse energy is calculated, and a pulse deflection signal is output to the optical modulator 25 so that only the insufficient pulse energy is irradiated onto the workpiece 10.

  The case where it is determined that the additional pulse laser beam is necessary is, for example, a case where the pulse energy obtained by the energy monitor 28 is equal to or lower than the threshold value. Further, the pulse energy set value and the threshold value can be arbitrarily set by the energy comparison circuit 29 according to the material of the workpiece 10, the machining thickness, and the like.

  For example, in the case of RCC (Resin Coated Copper), the threshold value is 85% of a predetermined pulse energy value, and in the case of FR4, the threshold value is 90% of the predetermined pulse energy value and resin (resin). The threshold value can be set to 95% of a predetermined pulse energy value. Note that the threshold value may be constant regardless of the material of the workpiece. Thus, the energy comparison circuit 29 can arbitrarily change and set the threshold value related to the pulse energy according to the processing conditions.

  The trigger pulse generation circuit 30 generates a trigger signal based on preset processing conditions and outputs the trigger signal to the laser oscillator 21 at a predetermined timing. The trigger pulse generation circuit 30 generates a trigger signal for additional shots on the laser oscillator 21 based on the emission instruction signal from the energy comparison circuit 29, and outputs the trigger signal to the laser oscillator 21 at a predetermined timing.

  Thereby, the additional pulse laser beam is irradiated from the laser oscillator 21, the energy of the pulse laser beam is adjusted for the additional shot by the optical modulator 25, and the workpiece 10 is irradiated with the adjusted pulse laser beam.

  For example, in the case of cycle irradiation such as conformal processing, the additional shot is irradiated to a required processing point after irradiation of a predetermined number of shots of pulsed laser light to each processing point on the processing target 10 is completed. The additional shots may be performed with the energy of the pulse laser beam corresponding to each, and in the case of continuous irradiation such as direct processing, after irradiation of a predetermined number of shots for each processing point on the processing target, Additional pulses may be irradiated. In the case of conformal processing, a processing point that requires an additional shot and adjustment information of a pulse deflection signal for the additional shot are stored as needed by providing an energy comparison circuit 29 or other storage means. After the irradiation of the number of shots is completed, an additional shot is irradiated to a necessary processing point.

  Thereby, even when energy such as energy loss or misfire is insufficient for irradiation of a predetermined number of shots of pulsed laser light, it is possible to irradiate the workpiece 10 with additional laser pulses of appropriate energy as additional shots.

<Additional shot pulse adjustment example>
Here, an example of adjustment of pulse laser light for additional shot will be described with reference to the drawings. FIG. 5 is a diagram for explaining an example of adjusting the energy of the additional shot in the first embodiment. As shown in FIG. 5, one or a plurality of pulsed laser beams applied to the processing point have a processing pulse energy having a predetermined processing pulse width and pulse height (peak output (KW)).

As shown in FIG. 5, in the case of an OK pulse, when the predetermined pulse energy value is 100%, the energy value becomes higher than the threshold value set according to the processing conditions such as the material of the processing target 10. In FIG. 5, a machining pulse having a predetermined pulse width T ₁ and a height H ₁ is generated in order to irradiate a predetermined pulse energy E ₁ .

Here, the pulse width T _1, the machining pulse for some reason becomes less weak pulse peak height H _2, the processing pulse energy value E ₂ is less than or equal to the threshold value. In this case, it is necessary to irradiate the additional shot, energy Ea of additional portion adjusts the pulse width _{T a} such that the difference _(E 1 -E ₂₎ of the _{E 1} and _{E 2.}

For example, if the pulse width T ₁ of the normal is about 10 microseconds, oscillated weak pulse, as shown in FIG. 5, if the processing pulse energy E ₂ is a predetermined 60%, additional pulse width T _a is set to 4 microseconds. That is, only the insufficient pulse energy is irradiated by adjusting the pulse width of the machining pulse.

  Thereby, laser processing can be executed with the desired total pulse energy, and the influence of the inner wall on the barrel shape and the metal film can be mitigated, and the quality can be stabilized.

<Second Embodiment>
Here, in the first embodiment described above, the pulse width of the machining pulse is adjusted. However, the adjustment may be performed by changing the height (peak output value H) of the machining pulse. Here, the above-mentioned content is demonstrated as 2nd Embodiment. FIG. 6 is a diagram illustrating an example of a schematic configuration of a laser processing apparatus according to the second embodiment. In FIG. 6, parts having the same functional configuration as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted here.

  The laser processing apparatus 40 according to the second embodiment shown in FIG. 6 has a peak output control circuit (peak output control unit) 41. The energy comparison circuit 42 compares the pulse energy obtained from the energy monitor 28 with a preset threshold value, and if it is equal to or less than the threshold value, an additional pulse is required, so that a trigger pulse is generated. An emission instruction signal for additional shots is generated and output to the circuit 30, and a pulse deflection signal is also output to the optical modulator 25. Further, the energy comparison circuit 42 calculates the shortage pulse energy from the difference information between the pulse energy obtained by the energy monitor 28 and the pulse energy set value when additional pulse laser light is required, and the shortage amount is calculated. A control signal for adjusting the height (peak output value) of the laser beam corresponding to the insufficient pulse energy is output to the peak output control circuit 41 so that only the pulse energy is irradiated onto the workpiece 10. .

  The laser oscillator 43 emits pulsed laser light with a peak output value set by the peak output control circuit 41 based on the trigger signal from the trigger pulse generating circuit 30.

Here, FIG. 7 is a diagram for explaining an adjustment example of the energy of the additional shot in the second embodiment. In the second embodiment, as shown in FIG. 7, when there is an NG shot with a pulse width T ₁ and a peak height H ₂ , an insufficient energy E _a (= E ₁₎ from the energy E _{2 of the} NG shot. -E ₂ ) is calculated, and a weak pulse signal having _a pulse height Ha that is the calculated energy is output. In the second embodiment, the pulse width is constant (T ₁ ).

  According to the second embodiment described above, by adjusting the peak output of the pulse laser light for additional shot, laser processing can be executed with the desired total pulse energy, and the inner wall is formed into a barrel shape or a metal film. Impact can be mitigated and quality stabilized. Thereby, the highly accurate laser processing to a process target object is realizable.

  The embodiment in the present invention is not limited to the above-described first and second embodiments, and for example, the first and second embodiments are used in an appropriate combination depending on processing conditions and the like. Also good. In that case, the above-described laser processing apparatus shown in FIG. 6 is used. In the present invention, the means for adjusting the pulse energy of the laser beam is not limited to the optical modulator described above, and for example, the signal width (time) of the trigger signal to the laser oscillator may be directly controlled. . Furthermore, in the present invention, it is also possible to change the pulse width (T) and peak output (H) of the pulse laser at the same time to make an additional shot that results in the insufficient energy Ea.

  As described above, according to the present invention, high-precision laser processing of a workpiece can be realized. Specifically, by adjusting the peak output of the pulse laser light for additional shots, laser processing can be executed with the desired total pulse energy, and the influence of the inner wall on the barrel shape and metal film is mitigated. Stabilization can be achieved. The control of the additional pulse of laser processing in the present invention can be applied to via formation for a printed circuit board or the like, but is also applied to general laser processing such as drilling, welding, cutting, and annealing of an object to be processed. be able to.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be changed.

It is a figure for demonstrating the mode of the compensation of the laser beam in the conventional laser processing apparatus. It is a figure which shows an example of the conventional drilling shape. It is a figure which shows an example of schematic structure of the laser processing apparatus in 1st Embodiment. It is a figure which shows an example of the timing chart at the time of a process. It is a figure for demonstrating the adjustment example of the energy of the additional shot in 1st Embodiment. It is a figure which shows an example of schematic structure of the laser processing apparatus in 2nd Embodiment. It is a figure for demonstrating the adjustment example of the energy of the additional shot in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Processed object 11 Metal film 12 Processed layer 20, 40 Laser processing apparatus 21, 41 Laser oscillator 22, 23, 24 Bending mirror 25 Optical modulator 26 Half mirror 27 Processing lens 28 Energy monitor 29, 42 Energy comparison circuit 30 Trigger Pulse generation circuit 31 Beam damper 41 Peak output control circuit

Claims (8)

In a laser processing apparatus that performs processing by irradiating a processing object with a pulse laser beam of a predetermined pulse energy,
A laser oscillator that emits a pulsed laser beam having a set output value;
A trigger pulse generator for outputting a trigger signal to the laser oscillator;
An optical modulator provided in an optical path for guiding the pulsed laser light from the laser oscillator to the workpiece, and adjusting a pulse width for each shot;
An energy monitor for detecting the pulse energy per shot;
The pulse energy and a threshold value with respect to the pulse energy can be set according to the processing conditions for the processing object, and the set threshold value is compared with the pulse energy detected by the energy monitor. When the pulse energy is less than or equal to the threshold value, a signal for outputting a shortage of pulse energy to the object to be processed is output to the trigger pulse generator and the optical modulator. A laser processing apparatus comprising: The energy comparison unit
The laser processing apparatus according to claim 1, wherein a shortage of pulse energy is calculated from difference information between the pulse energy obtained by the energy monitor and the predetermined pulse energy. The energy comparison unit
Output a signal for emitting an additional pulse laser beam to the trigger pulse generator,
The pulse width of the pulse laser beam emitted from the laser oscillator is adjusted by the optical modulator so that the insufficient pulse energy is applied to the object to be processed. The laser processing apparatus as described. A peak output control unit for controlling a peak output value of the laser oscillator;
The energy comparison unit
Outputting a control signal for adjusting the peak output value of the pulsed laser light emitted by the laser oscillator to the peak output control unit so that the insufficient pulse energy is irradiated to the workpiece. The laser processing apparatus according to any one of claims 1 to 3, wherein the laser processing apparatus is characterized in that: In a laser processing method for performing processing by irradiating a workpiece with a pulse laser beam corresponding to a predetermined pulse energy,
A trigger pulse generation stage for outputting a trigger signal from the trigger pulse generator to the laser oscillator;
An emission step of emitting a pulsed laser beam having a peak output value set by the trigger signal from the laser oscillator;
A pulse width adjusting step of adjusting a pulse width for each shot by an optical modulator provided in an optical path for guiding the pulsed laser light from the laser oscillator to the workpiece;
A detection step of detecting pulse energy for each shot by an energy monitor;
The pulse energy and a threshold value with respect to the pulse energy can be set according to the processing conditions for the processing object, and the set threshold value is compared with the pulse energy detected by the energy monitor. When the pulse energy is less than or equal to the threshold value, an energy comparison step of outputting a signal for causing the workpiece to output insufficient pulse energy to the trigger pulse generator and the optical modulator. A laser processing method comprising: The energy comparison step includes
6. The laser processing method according to claim 5, wherein a shortage of pulse energy is calculated from difference information between the pulse energy obtained by the energy monitor and the predetermined pulse energy.   The pulse width of the pulse laser beam emitted from the laser oscillator by the optical modulator is adjusted so that the insufficient pulse energy is irradiated to the workpiece. Laser processing method.   The peak output value of the pulse laser beam emitted from the laser oscillator is adjusted so that the insufficient pulse energy is applied to the object to be processed, according to any one of claims 5 to 7. The laser processing method as described.

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