JP2001062583A - Processing laser device equipped with optical path changing means - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing laser device which can stop irradiation of a laser light to a workpiece without installing a shutter mechanism, and prevent variation of output power of the laser light even if laser light irradiation to the workpiece is stopped. SOLUTION: When a workpiece is irradiated with a laser light, a mirror 8 is retreated to a solid line position. The laser light ejected from a wavelength converting element (nonlinear optical system crystal) 2 is incident on an fθ lens 5 via an enlarging collimator 3 and a galvano mirror 4, and irradiates a workpiece 6. When the laser light irradiation to the workpiece 6 is stopped, the mirror 8 is inserted to a dotted line position. The laser light ejected from the wavelength converting element 2 is incident on the concave lens 9 via the enlarging collimator 3 and the mirror 8 so as to lower power density, and is incident on a laser light receiver 11 so as to absorb the energy. Instead of the mirror 8, a prism, a parallel plate and the like can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for generating a harmonic laser beam using a nonlinear optical crystal and irradiating an object to be irradiated such as a multilayer printed circuit board with a laser beam to remove holes and markings. The present invention relates to a processing laser device that performs a processing operation.

[0002]

2. Description of the Related Art A high-output, high-repetition-rate ultraviolet laser device having a wavelength of 262 to 355 nm using wavelength conversion by a non-linear optical crystal is used as a laser device for drilling a printed circuit board or the like. The general configuration is a wavelength of 1064 nm
The Nd: YAG laser, Nd: YVO ₄ laser or a wavelength 1047 nm, Nd: a YLF laser as an excitation source, to generate a second harmonic by a nonlinear optical crystal, but to further generate a third to fourth harmonic is there. Third
LBO and GDYCOB crystals as harmonic generation crystals,
For the fourth harmonic, BBO, CLBO crystal or the like is used. The wavelength-converted light is shaped and applied to a workpiece such as a printed board via a galvanomirror and an fθ lens.

FIG. 8 is a diagram showing a schematic configuration of the above-mentioned processing laser device. Although only one wavelength conversion element is shown in FIG. 8, a wavelength conversion element for generating the third or fourth harmonic is provided in addition to the wavelength conversion element for generating the second harmonic as described above. be able to. As shown in FIG. 8, laser light emitted from a laser light source 21 is condensed by a condenser lens 22 and enters a wavelength conversion element (nonlinear optical crystal) 23. A part of the laser light incident on the wavelength conversion element 23 is wavelength-converted and emitted from the wavelength conversion element 23, and the emitted light is shaped into an appropriate beam diameter by the beam shaping lens 24.

[0004] The laser beam shaped by the beam shaping lens 24 is applied to a processing head 2 comprising a galvanomirror 25.
6 and is driven by the galvanomirror 25 to control the movement of the laser beam on the workpiece. The laser beam scanned by the galvanometer mirror 25 is transmitted to the fθ lens 27
The workpiece 28 is irradiated on the printed circuit board or the like through the through-hole to perform processing such as drilling. When the above laser device is used for processing such as drilling of a substrate, the laser irradiation is stopped on a time scale of several to several tens of seconds by moving the processing position or replacing the substrate, and then irradiating the laser light. It is necessary to do the work of restarting. The method of stopping the laser irradiation is usually to turn on / off the emission of the laser light from the laser light source 1 by a Q switch, or to control the fundamental laser light emitted from the laser light source 1 by a light shielding means such as a shutter. Shield.

[0005]

As described above, when the laser irradiation is stopped or the fundamental laser light is blocked by the Q switch, shutter, or the like, the laser light does not enter the wavelength conversion element 23. Therefore, the wavelength-converted light is not absorbed by the wavelength conversion element 23, and the temperature of the wavelength conversion element 23 decreases. Therefore, when the laser irradiation is resumed after the pause, when the laser light is incident on the wavelength conversion element 23, the wavelength conversion element (nonlinear optical crystal) 23 is self-heated due to the generation of the wavelength-converted laser light. Temperature changes. Since the refractive index of the nonlinear optical crystal changes depending on the temperature, when the temperature changes, the phase matching angle shifts and the output power fluctuates. Due to this variation, defects occur in the hole depth and the processing shape in the processing of via holes and the like. It is demanded that the fluctuation of the output power be within 10%. Note that if the processing is started after the output power is stabilized, the above problem does not occur, but the throughput decreases.

On the other hand, if a light-shielding means such as a shutter is provided at the position A or B in FIG. 8 to shield the wavelength-converted light, even when the irradiation of the laser light to the workpiece 28 is stopped, the wavelength is not changed. A laser beam is always incident on the conversion element (nonlinear optical crystal) 23, and the temperature control of the crystal becomes easy. When the laser beam irradiation is restarted, the shutter may be opened. With this method, the output power does not fluctuate due to the crystal temperature change when the laser beam is incident as described above. However, providing a light shielding means such as a shutter on the emission side (A or B in FIG. 8) of the wavelength conversion element 23 has the following problems. The wavelength of the laser light after the wavelength conversion is short. Short-wavelength light is generally easily absorbed by a substance, and if absorbed, the temperature of the substance increases. For this reason, it is necessary to increase the thickness of the shutter or to provide a cooling means for cooling the shutter in order to prevent deformation due to heating.

[0007] While the shutter is moving to open and close the optical path, it is difficult to control the irradiation of the laser light unless emission of the laser light from the nonlinear optical crystal is stopped. In general,
If the time is 0.1 seconds or less, a large change in the crystal temperature does not occur even if the laser injection to the crystal is stopped. That is, when the shutter is provided, it is necessary to move the shutter within about 0.1 second. Normally, a shutter for blocking light is driven by a driving unit such as an air cylinder or a motor.However, in order to prevent deformation due to the above-described causes, a thick and heavy shutter is moved at high speed, or a water-cooling or air-cooling cooling unit is used. Considering that the shutter mechanism is provided, the size of the shutter mechanism increases, which causes an increase in the size and cost of the apparatus.

As described above, when the laser irradiation is stopped or the fundamental laser light is blocked by the Q switch, the shutter, or the like, the output power of the laser light emitted from the wavelength conversion element 23 fluctuates, and There was a problem that a malfunction occurred. In addition, when a shutter is provided on the emission side of the wavelength conversion element, there is a problem that the shutter mechanism becomes large and cost increases. The present invention has been made in order to solve the above-described problems of the related art, and can irradiate a workpiece with laser light without providing a large and expensive shutter mechanism. An object of the present invention is to provide a processing laser device in which the output power of laser light does not fluctuate even when the irradiation of laser light to a workpiece is stopped.

[0009]

According to the present invention, the above-mentioned problems are solved as follows. An optical path changing means, such as a mirror, for changing the optical path of the laser light is provided on the emission side of the wavelength conversion element (nonlinear optical crystal). When the workpiece is not irradiated with the laser light, the laser light is changed by the optical path changing means. The light path is changed to irradiate the laser light receiving means. In the present invention, when the workpiece is not irradiated with the laser light as described above, the optical path of the laser light is changed by the optical path changing unit without stopping the laser light from the laser light source,
Since the laser beam is applied to the laser beam receiving means, the laser beam always enters the wavelength conversion element (nonlinear optical crystal).
Therefore, when the irradiation of the workpiece with the laser beam is started, the temperature of the crystal does not change, and the fluctuation of the output power can be eliminated.

[0010]

FIG. 1 is a diagram showing an embodiment of the present invention. This embodiment shows an embodiment in which a light path is changed using a mirror. In FIG. 1, a laser and a fundamental laser beam emitted from a modulator 1 enter a wavelength conversion element 2 composed of a nonlinear optical crystal, and a part of the wavelength is converted into a harmonic. Light emitted from the wavelength conversion element 2 enters the galvanometer mirror 4 via the magnifying collimator 3. The galvanometer mirror 4 includes, for example, an X-axis mirror 32 driven by an X-axis scanner 31 and a Y-axis mirror 34 driven by a Y-axis scanner 33 as shown in FIG. By driving the mirror 34, the laser beam is scanned so as to irradiate a processing position on the workpiece. The laser beam scanned by the galvanometer mirror 4 is applied to the workpiece 6 via the fθ lens 5.

In the processing laser apparatus having the above-described configuration, in this embodiment, a mirror 8 driven by an air cylinder 7 is provided between the magnifying collimator 3 and the galvanometer mirror 4. When the irradiation of the laser beam to the workpiece 6 is stopped, the laser and the Q switch QSW provided in the modulator 1 are controlled for a short time (for example, 0.1 seconds when no large change occurs in the crystal temperature). The laser beam emission is stopped, and the air cylinder 7 is driven to insert the mirror 8 at the position indicated by the dotted line in FIG. 1 to change the optical path of the laser beam. When the mirror 8 is inserted into the optical path of the laser light, the laser light is reflected by the mirror 8 and enters the concave lens 9 as shown by a dotted line in FIG. Then, the light flux is spread by the concave lens 9 to reduce the power density, and the light enters the laser light receiver 10 and its energy is absorbed. Since the temperature of the laser beam receiver 10 rises by absorbing the laser beam, it is cooled by cooling water (air cooling may be used) as shown in FIG. The light reflected by the mirror 8 may be incident on an output monitor to monitor the output power of the laser light. When the workpiece 6 is irradiated with the laser light again, the laser and the Q switch QSW provided in the modulator 1 are controlled as described above to stop emission of the laser light for a short time, and the air cylinder 7 is driven. The mirror 8 is retracted to the position indicated by the solid line in FIG.

FIG. 3 is a time chart showing the operation of this embodiment. After performing processing by irradiating the workpiece with laser light, for example, when loading a substrate that is a workpiece, changing the number of repetitions of laser light irradiation, and moving the irradiation position of laser light, First, as shown in FIG. 1B, the Q switch QS provided in the laser and the modulator 1
W is turned off for a short time, during which the mirror 8 is moved as shown in FIG. 1C and inserted at the dotted line position in FIG. Next, as shown in FIG.
Turn SW on. As a result, the laser light is reflected by the mirror 8 and is reflected by the laser light receiver 1 on the optical path shown by the dotted line in FIG.
Incident at 0. Therefore, the workpiece 6 is not irradiated with the laser light as shown in FIG.

When the loading of the substrate, the change in the number of repetitions of laser light irradiation, and the movement of the laser light irradiation position are completed, the laser Q switch QSW is turned off again for a short time,
The mirror 8 is moved and retracted to the position indicated by the solid line in FIG. Next, the Q switch QSW is turned on. Thereby, the workpiece 6 is irradiated with the laser beam again. In FIG. 3, when the irradiation of the laser beam to the workpiece 6 is stopped, the Q switch is turned off, then the panel is loaded, and then the mirror is moved. When the irradiation of the laser beam is stopped, the mirror 8 may be moved first after the Q switch is turned off, and then the panel may be loaded.

In this embodiment, as described above, the mirror 8 for changing the optical path of the laser light is provided, and when the workpiece 6 is not irradiated with the laser light, the mirror 8 changes the optical path of the laser light. Then, since the laser beam is applied to the laser beam receiver 10, the laser beam is always incident on the wavelength conversion element 2 except for a short time for moving the mirror 8. For this reason, when the workpiece 6 is irradiated with the laser beam, the temperature of the wavelength conversion element (nonlinear optical crystal) 3 does not change and the output power does not change.

In the above embodiment, a case has been described in which the optical path of the laser light is changed by inserting a mirror, but various optical components other than the above-described mirror can be used as means for changing the optical path of the laser light. . Hereinafter, a modified example of the above embodiment will be described. FIG. 4 shows an embodiment in which the optical path is changed by inserting a prism in the optical path of the laser light. In FIG. 4, the laser, the modulator 1, the magnifying collimator 3, the galvanomirror 4, etc. shown in FIG. 1 are omitted. FIG. 3A shows a state in which the workpiece 6 is irradiated with a laser beam, and FIG.
2 shows a state in which irradiation of laser light to the laser beam is stopped.
In the figure, reference numeral 7 denotes an air cylinder, and 8a denotes a prism. The air cylinder 7 drives the prism 8a to move it to the position shown in FIG.

When the workpiece 6 is irradiated with laser light,
The prism 8a is retracted from the laser beam path by the air cylinder 7 as shown in FIG. Thereby, the laser beam emitted from the wavelength conversion element 2 is irradiated on the workpiece 6 via the fθ lens 5. When stopping the irradiation of the workpiece 6 with the laser beam, the prism 8a is inserted into the laser beam path. As a result, the optical path of the laser light is changed as shown in FIG. 2B, the light flux of the laser light is expanded by the concave lens 9, the power density is reduced, and the laser light
At 0, the energy is absorbed.

FIG. 5 shows an embodiment in which the optical path is changed by rotating a mirror inserted in the optical path of the laser beam. 5, the laser, modulator 1, magnifying collimator 3, galvanomirror 4, etc. shown in FIG. 1 are omitted as in FIG. FIG. 3A shows the workpiece 6.
FIG. 3B shows a state in which the irradiation of the laser beam to the workpiece 6 is stopped. In the figure, reference numeral 11 denotes a motor, and 8b denotes a mirror. The motor 11 rotates the mirror to a position shown in FIG. Workpiece 6
When the laser beam is applied to the mirror 8b, the mirror 8b is rotated to the position shown in FIG. As a result, the laser beam emitted from the wavelength conversion element 2 is reflected by the mirror 8 b and is irradiated on the workpiece 6 via the fθ lens 5. When the irradiation of the laser beam to the workpiece 6 is stopped, the mirror 8b is rotated to the position shown in FIG. Thereby, the laser light is reflected by the mirror 8b and enters the concave lens 9. Then, the light flux is spread by the concave lens 9 to reduce the power density, and the light enters the laser light receiver 10 and its energy is absorbed.

FIG. 6 shows an embodiment in which the optical path is changed by rotating a prism inserted in the optical path of the laser beam. 6, the laser, modulator 1, magnifying collimator 3, galvanomirror 4, etc. shown in FIG. 1 are omitted as in FIG. FIG. 2A shows a state in which the workpiece 6 is irradiated with laser light, and FIG. 2B shows a state in which the irradiation of the workpiece 6 with laser light is stopped. In the figure, reference numeral 11 denotes a motor, and reference numeral 8c denotes a prism. The motor 11 rotates the prism 8c to a position shown in FIG.

When irradiating the workpiece 6 with a laser beam,
The motor 8 rotates the prism 8c to the position shown in FIG. As a result, the laser beam emitted from the wavelength conversion element 2 enters the fθ lens 5 via the prism 8c, and irradiates the workpiece 6 via the fθ lens 5. When stopping the irradiation of the laser beam on the workpiece 6,
The prism 8c is rotated to the position shown in FIG. As a result, the laser light is transmitted through the prism 8c to the concave lens 9
Incident on. Then, the light flux is spread by the concave lens 9 and the power density is reduced, and the light flux enters the laser light receiver 10,
That energy is absorbed.

FIG. 7 shows an embodiment in which the optical path is changed by inserting a parallel plate into the optical path of the laser beam. In FIG. 7, similarly to FIG. 4, the laser and the modulator 1, the magnifying collimator 3, and the galvanometer mirror 4 shown in FIG.
Etc. are omitted. FIG. 2A shows a state in which the workpiece 6 is irradiated with laser light, and FIG. 2B shows a state in which the irradiation of the workpiece 6 with laser light is stopped. In the figure, 7 is an air cylinder, 8d is a parallel plate,
M1, M2 and M3 are mirrors, and the air cylinder 7 drives the parallel plate 8d to move it to the position shown in FIG.

When the workpiece 6 is irradiated with a laser beam,
As shown in FIG.
d is retracted from the laser beam path. As a result, the laser light emitted from the wavelength conversion element 2 is reflected by the mirrors M1, M2, M3.
, And is incident on the workpiece 6 via the fθ lens 5. When stopping the irradiation of the workpiece 6 with the laser beam, the parallel plate 8d is inserted into the laser beam path. This changes the optical path of the laser light as shown in FIG. 2B, and the laser light enters the concave lens 9 via the mirror M4. Then, the light flux is spread by the concave lens 9 to reduce the power density, and the light enters the laser light receiver 10 and its energy is absorbed.

In the above embodiment, when the optical path is changed using a prism, if the prism is processed so as to partially spread light similarly to a concave lens,
The concave lens 9 provided on the incident side of the laser receiver 11 may be unnecessary. As a means for changing the optical path of the laser beam, other than the means described in the above embodiment, for example, a polygonal mirror (polygon mirror) rotated by a motor (for example, a stepping motor) may be used,
An OQ switch (acoustic-optical Q switch) or the like can also be used.

[0023]

As described above, in the present invention, the means for changing the optical path of the laser light is provided, and when the workpiece is not irradiated with the laser light, the optical path of the laser light is changed by the optical path changing means. Since the laser beam is irradiated to the laser beam receiving means by changing the laser beam, the laser beam is always incident on the nonlinear optical crystal even when the workpiece is not irradiated with the laser beam. Therefore, when the irradiation of the workpiece with the laser beam is started, the temperature of the crystal does not change, and the fluctuation of the output power can be eliminated. Further, a large and expensive shutter mechanism is not required, and the size and cost of the apparatus can be reduced. Furthermore, if a mirror, a prism, a parallel plate, or the like is used as the optical path changing means, the temperature of the laser light does not rise extremely even when the laser light is irradiated, so that cooling of the optical path changing means is not particularly considered.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention in which an optical path is changed using a mirror.

FIG. 2 is a diagram illustrating a configuration example of a galvanomirror.

FIG. 3 is a time chart showing the operation of the embodiment of the present invention.

FIG. 4 is a diagram showing an embodiment in which an optical path is changed by inserting a prism.

FIG. 5 is a diagram showing an embodiment in which an optical path is changed by rotating a mirror.

FIG. 6 is a diagram showing an embodiment in which an optical path is changed by rotating a prism.

FIG. 7 is a diagram showing an embodiment in which an optical path is changed by inserting a parallel plate.

FIG. 8 is a diagram showing a schematic configuration of a processing laser device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser and modulator 2 Wavelength conversion element (nonlinear optical crystal) 3 Magnifying collimator 4 Galvanometer mirror 5 fθ lens 6 Workpiece 7 Air cylinder 8, 8b Mirror 8a, 8c Prism 8d Parallel plate

Claims (1)

[Claims] 1. A process for generating a harmonic laser beam by a non-linear optical crystal, intermittently irradiating the object to be irradiated with the harmonic laser beam, and removing holes or markings from the object to be irradiated. A laser device, provided on the emission side of the nonlinear optical crystal, an optical path changing means for changing the optical path of the laser light, and when not irradiating the laser light from the laser apparatus, the optical path changing means changes the optical path of the laser light. A processing laser device provided with an optical path changing means, wherein the laser light is changed and irradiated to a laser light receiving means.