JP2003053564A - Method and device for controlling laser beam machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the machining quality by always irradiating a machined face with a laser beam having a necessary and sufficient quantity of energy without causing a short nor excessive energy supply. SOLUTION: A part of laser beam 12 with which a work 16 is irradiated is branched from a laser oscillator 10, the energy is detected and the laser beam 12 is so controlled that the energy becomes a prescribed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing control method and apparatus for controlling laser light emitted from a laser oscillator to a workpiece, and more particularly to a laser drilling machine using a pulse laser oscillator. The present invention relates to a laser processing control method and apparatus suitable for use in, capable of improving the stability of processing quality.

[0002]

2. Description of the Related Art In recent years, a laser drilling machine for providing via holes and through holes in a printed wiring board by using pulsed laser light has been put into practical use.

In such a laser processing apparatus, in order to maintain the processing quality, it is important to control the energy applied to the workpiece.

Therefore, in the laser drilling process, a work referred to as process condition setting is performed in advance to determine the width of the pulse irradiated by the laser oscillator, the number of pulses, etc. and register them as process condition data. Then, the laser oscillator is operated based on the processing conditions to irradiate the processed surface with laser light.

However, there are variations in the output energy of the laser oscillator, and when the characteristics of the oscillator are deteriorated, a phenomenon called pulse omission in which the irradiation energy is significantly insufficient may occur.

In the conventional processing apparatus, since there is no means for detecting these variations and lack of energy, processing defects are generated.

In order to solve such a problem, the applicant has disclosed in Japanese Patent No. 2864005 that when the energy of the laser beam is extremely insufficient, additional pulse irradiation is performed as shown in FIG. We have proposed a pulse-added machining control device that prevents shortages. In FIG. 1, P1 to
P6 and P7 to P12 are additional pulses that are added because the first and second regular pulses are generated, and P13 is a second missing pulse at P10 and P11, respectively.

By using this pulse-addition type machining control device, machining defects due to lack of energy (small hole diameter, residue on the bottom surface of the hole) can be prevented.

[0009]

However, since the energy is adjusted on a pulse-by-pulse basis, if the energy shortage is less than one pulse, quality deterioration due to excessive energy irradiation cannot be avoided. Further, since the pulse is additionally irradiated, it takes extra time, which causes a problem of impeding productivity.

The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to constantly irradiate a laser beam having a necessary and sufficient energy on a processing surface to stabilize the processing quality.

[0011]

According to the present invention, in a laser processing control method for controlling a laser beam applied to a workpiece from a laser oscillator, a part of the laser beam is branched and its energy is reduced. The problem is solved by detecting and performing feedback control of the laser light so that the energy becomes a predetermined value.

The present invention is also a laser processing control device for controlling a laser beam applied to a workpiece from a laser oscillator, and means for branching a part of the laser beam,
The problem is also solved by providing means for detecting the energy of the branched laser light and means for feedback controlling the laser light so that the detected energy has a predetermined value.

Further, the means for controlling the laser light includes an optical path switching means inserted in the optical path of the laser light and a beam dump for absorbing unnecessary laser light eliminated by the optical path switching means. Is.

Further, the switching timing of the optical path switching means is delayed according to the rising characteristics of the laser light.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

In the present embodiment, as shown in FIG. 2, in the laser processing control device for controlling the laser light 12 applied to the workpiece 16 from the laser oscillator 10, a part of the laser light is branched. Half mirror 20, an energy detection element 22 for detecting the energy of the laser light branched by the half mirror 20, a high-speed optical path switching element 24 inserted in the optical path of the laser light 12, and the high-speed optical path. The beam dump 26 for absorbing the unnecessary laser light rejected by the switching element 24 and the energy detected by the energy detecting element 22 have a predetermined value.
An oscillation control device 30 for feedback-controlling the laser oscillator 10 and the high-speed optical path switching element 24, and an upper processing control device 32 for inputting a necessary energy amount for each pulse immediately before pulse oscillation are provided. In the figure, 1
Reference numeral 4 is a focus lens.

As the energy detecting element 22, for example, an optical sensor is used and its output is electrically integrated,
Alternatively, it is also possible to use a thermopile, which has a slow response but converts energy into heat and can be directly detected.

As the high-speed optical path switching element 24, for example, an acoustic modulator (AOM) can be used.

As the beam dump 26, one having a function of a photodetector for detecting a laser waveform can be used.

The operation will be described below with reference to FIG.

The required energy amount for each pulse is input to the oscillation control device 30 from the host processing control device 32 immediately before pulse oscillation.

When the oscillation control device 30 receives the laser processing start signal (FIG. 3 (A)) from the processing control device 32, it turns on the operation signal (FIG. 3 (B)) of the laser oscillator 10 to turn on the laser. The light 12 is output. At the same time, the high-speed optical path switching element 24 is controlled to guide the laser light to the processed surface as shown in FIG.

When the output rise is slow due to the characteristics of the laser oscillator 10, such as an RF type oscillator, the switching timing of the high-speed optical path switching element 24 is delayed by the time t _D , and the laser light output is After reaching the peak level, the laser light is guided to the processed surface. The delay control of the switching timing is performed in a fixed time width according to the characteristics of the laser oscillator 10 and the laser waveform detected by the photodetector provided on the beam dump 26 side of the high-speed optical path switching element 24 (see FIG. 3). From (C)), it is possible to control in real time.

At the same time that the laser light is guided to the processed surface, a part of the energy detection element 22 is also branched and irradiated. The energy of the irradiated pulsed light is time-integrated by the detection element 24 (FIG. 3 (D)) and exceeds the preset energy level, and at the same time, the operation signal of the laser oscillator 10 is turned off, and at the same time, as shown in FIG. As shown, the high speed optical path switching element 24 is switched to the beam dump 26 side.

In this embodiment, since the irradiation state of the laser light is controlled by using the high-speed optical path switching element 24,
High-speed and reliable feedback control is possible.
The means for controlling the irradiation state of the laser light is not limited to this, and for example, the beam dump 26 can be mechanically moved in and out of the optical path. The optical path switching means is also AOM
Not limited to.

In the above embodiment, the present invention is
It was applied to a laser drilling machine using a pulse type laser oscillator, the application target of the present invention is not limited to this,
The present invention can be similarly applied to general laser processing apparatuses using a continuous oscillation type laser oscillator such as a laser cutting machine. Further, the means for branching a part of the laser beam applied to the workpiece is not limited to the half mirror.

[0027]

According to the present invention, since the laser beam of necessary and sufficient energy is always applied to the machined surface without supplying the energy shortage or the excessive energy, the machining quality is stable. Further, in the pulse-addition type processing control device, it takes extra time to output the additional pulse, but according to the present invention, such an extra time is not necessary, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the operation of a pulse addition type machining control device proposed by the applicant in Japanese Patent No. 2864005.

FIG. 2 is a block diagram showing an overall configuration of an embodiment of a laser processing control device according to the present invention.

FIG. 3 is a timing chart showing signal waveforms of various parts of the embodiment.

FIG. 4 is an optical path diagram showing a state in which unnecessary laser light is switched to a beam dump side by a high-speed optical path switching element in the embodiment.

[Explanation of symbols]

10 ... Laser oscillator 12 ... Laser light 16 ... Workpiece 20 ... Half mirror 22 ... Energy detecting element 24 ... High-speed optical path switching element 26 ... Beam dump 30 ... Oscillation control device 32 ... Machining control device

Claims (4)

[Claims] 1. A laser processing control method for controlling laser light applied to a workpiece from a laser oscillator, wherein a part of the laser light is branched to detect its energy, and the energy is a predetermined value. The laser processing control method is characterized by performing feedback control of the laser light so that 2. A laser processing control device for controlling a laser beam applied to a workpiece from a laser oscillator, and means for branching a part of the laser beam and detecting energy of the branched laser beam. A laser processing control device comprising: means, and means for feedback controlling the laser light so that the detected energy has a predetermined value. 3. The means for controlling the laser light includes an optical path switching means inserted in the optical path of the laser light, and a beam dump for absorbing the unnecessary laser light eliminated by the optical path switching means. The laser processing control device according to claim 2. 4. The laser processing control apparatus according to claim 3, wherein the switching timing of the optical path switching means is delayed according to the rising characteristics of the laser light.