JP4251742B2 - Laser processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser processing apparatus that performs processing by rotating a mirror around an axis and positioning a laser beam oscillated from a laser oscillator at a predetermined position of a workpiece.
[0002]
[Prior art]
In a laser processing apparatus such as a laser drilling machine that drills a printed board or the like with a laser beam, a scanner that controls positioning of a mirror around an axis is used to guide the laser beam to a predetermined position. FIG. 3 is an external view of a scanner arrangement portion in a conventional laser drilling machine. The scanner includes a scanner body 1 and a scanner controller 2, and the scanner body 1 is supported on a base 3 of a laser drilling machine. The scanner body 1 includes a motor 4, a rotation angle sensor 5 (hereinafter referred to as a sensor) that detects the rotation angle of the motor 4, and a reflection surface 7 a that is disposed at the end of the rotation shaft 6 connected to the motor 4. The mirror 7 is provided, and is connected to the scanner controller 2 via the cable 8. The scanner controller 2 is connected to the controller 9 of the laser drilling machine. An fθ lens 10 is disposed between the mirror 7 and the table 13. The fθ lens 10 is arranged so that its center is in the vertical direction and coincides with the center of the mirror 7, and the laser light 12 reflected by the mirror 7 incident on a predetermined range (hereinafter referred to as a control range) is converted into the fθ lens. 10 is emitted as a laser beam 12 in a vertical direction substantially parallel to the central axis of 10. The table 13 moves in the horizontal direction perpendicular to the central axis of the fθ lens 10. A printed circuit board 14 as a work is fixed to the table 13.
[0003]
Next, the operation of the conventional laser drilling machine will be described.
First, the controller 9 moves the table 13 to position the printed circuit board 14 in the control range. Next, the scanner controller 2 is commanded to determine the angle of the reflecting surface 7a (for example, an angle with respect to a vertical axis). The scanner controller 2 supplies a current to the motor 4 via the cable 8 while detecting the rotation angle of the rotary shaft 6 by the sensor 5 based on a command from the controller 9, and positions the reflecting surface 7a at the commanded position. To do. When the reflecting surface 7a is positioned at a predetermined position, the controller 9 outputs laser light 12 from a laser oscillator (not shown). The outputted laser beam 12 is reflected by the reflecting surface 7 a and enters the fθ lens 10, and the emitted laser beam 12 enters the surface of the printed board 14 substantially perpendicularly to make a hole in the printed board 14. After processing one hole, the output of the laser beam 12 is stopped. Then, the reflecting surface 7a is positioned (scanned) at the processing position of the next hole, and the laser beam 12 is output to process the next hole. In the same manner, holes in the control range are machined. Then, after the processing of the holes in the control range is completed, the table 13 is moved, the printed board 14 is positioned in the next control range, and the holes in the next control range are processed. Thereafter, the above operation is repeated until all the holes have been processed. Since the time required for positioning the reflecting surface 7a is much shorter than the time required for positioning the table 13, the work efficiency is improved when the hole is machined as described above.
[0004]
As the sensor 5, a capacitance type sensor having a simple structure, a high response speed, and a high positioning accuracy is often used. The capacitance type sensor has a configuration in which a dielectric is fixed to a rotating shaft, and the dielectric is sandwiched between at least one pair of electrodes facing each other. When the rotating shaft 5 rotates, the insertion area of the dielectric sandwiched between the plates changes, and the change in the capacitance between the plates accompanying this change is detected to change the angle of the rotating shaft 6. Convert. For example, Japanese Patent Laid-Open No. 7-55500 discloses a configuration of such a rotation angle sensor.
[0005]
[Problems to be solved by the invention]
By the way, the value of the capacitance between the electrode plates described above depends on the dielectric constant of air existing between the electrode plates, the distance between the electrode plates, and the like. For this reason, even if the insertion area of the dielectric sandwiched between the electrode plates is the same, the capacitance value changes as the environmental conditions (especially humidity) such as temperature and humidity change, resulting in zero drift and scale drift. Will occur. As shown in FIG. 4A, zero drift is a phenomenon in which the range of reflected light indicated by a solid line rotates to one side as indicated by a dotted line, and scale drift is such that the reflection angle indicated by a solid line is indicated by a dotted line. In any case, an error occurs in the detected value, and a processing error occurs accordingly.
[0006]
Therefore, as shown in FIG. 5, for example, the scanner body 1 is surrounded by a U-shaped cover 15, and at the time of processing, dry air indicated by an arrow is supplied to the inside of the cover 15 or the cover 15 is kept warm by a heater. Has been tried. However, in particular, in the case of a sensor in which the electrode plate is configured on a printed circuit board having a hygroscopic property such as a glass epoxy material, the surrounding hole is absorbed while the laser drilling machine is stopped at night or the like, and the laser hole is The performance of the sensor 4 may change over time from the start of the light machine until the electrode plate is sufficiently dried. Further, since the time constant of the temperature change due to the heat generation of the coil is long, it takes 5 to 10 hours from the start of operation until the operation is stabilized, and the positioning accuracy is changed by about ± 20 μm.
[0007]
For this reason, when it is necessary to make the position accuracy of the hole to be processed within ± 10 μm, the test piece such as an acrylic plate is scanned every 30 minutes to 1 hour from the start of operation until the operation becomes stable. The position of the hole was measured with a high-magnification TV camera, and the rotation angle was corrected. Moreover, even after the operation became stable, the rotation angle was corrected every 3 to 5 hours. In addition, when the position accuracy of the hole to be processed needs to be within ± 5 μm like a high-density substrate, the rotation angle is corrected every 30 minutes even after the operation becomes stable. And since the said correction | amendment operation | work requires 5-10 minutes for every time, the apparatus operation rate fell to 67-83% at maximum.
[0008]
An object of the present invention is to solve the above-described problems in the prior art and provide a laser processing apparatus that is excellent in processing accuracy and can improve the apparatus operating rate even if the environmental conditions of the scanner body change.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, there is provided a laser for processing a workpiece by irradiating a laser beam oscillated from a laser oscillator to a mirror which can be positioned around an axis and reflecting the laser beam by the mirror. In the processing apparatus, a beam irradiation device for irradiating a laser beam different from the laser beam used for processing and a first light receiving device are provided, and the laser beam from the beam irradiation device is parallel to the reflecting surface of the mirror. Irradiation toward the reflection surface on the back side of the reflection surface of the mirror, and the first light receiving device can receive the laser beam on the opposite side of the beam irradiation device with respect to an axis perpendicular to the reflection surface of the mirror placed, from the position of the laser beam received by the first light receiving device detects the rotational displacement amount of the mirror, also a beam splitter is provided between the said beam irradiation device and the mirror A second light receiving device is disposed at a position where the reflected light from the beam splitter can be received, a displacement amount of the beam irradiation device is detected from a position of the laser beam received by the second light receiving device, and the mirror Based on the rotational displacement amount of the beam and the displacement amount of the beam irradiation device, the mirror positioning angle at the time of processing is corrected .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the illustrated embodiments.
FIG. 1 is an apparatus configuration diagram of a scanner arrangement unit in a laser drilling machine according to the present invention. Components having the same or the same functions as those in FIG.
[0014]
A reflecting surface 7b parallel to the reflecting surface 7a is formed on the surface of the mirror 7 opposite to the reflecting surface 7a. Further, a laser light source 21, a beam splitter or half mirror 22 and a first optical sensor 23 are arranged so as to face the reflecting surface 7b. The beam splitter 22 reflects about 50% of the laser beam 24 output from the laser light source 21 and passes the rest. A second optical sensor 25 is disposed at a position substantially perpendicular to the beam splitter 22. The optical sensors 23 and 25 are connected to the controller 9.
[0015]
The reference position of the reflecting surface 7a is a position where the reflecting surface 7a is 45 degrees with respect to the vertical line. When the reflecting surface 7a is positioned at the reference position, the incident angle of the laser beam 12 and the laser beam 24 of the laser light source 21 are determined. The output direction, the optical sensor 23 and the optical sensor 25 are positioned in advance as follows. That is, the incident angle of the laser beam 12 is positioned so that the laser beam 12 reflected by the reflecting surface 7 a proceeds in the vertical direction and enters the center of the fθ lens 10. The laser light source 21 is positioned so that the laser beam 24 to be output is directed toward the rotation axis O of the mirror 7. The beam splitter 22 is positioned at 45 degrees with respect to the laser beam 24. The optical sensor 23 is positioned so that the laser beam 24 reflected by the reflecting surface 7b is incident on the center A0. The optical sensor 25 is positioned so that the laser beam 24 reflected by the beam splitter 22 is incident on the center B0.
[0016]
Next, the operation of the present embodiment will be described.
FIG. 2 is a diagram for explaining measurement specifications in the present invention. Here, the thickness of the mirror 7 is set to 0 for easy understanding. The distance between the center A of the optical sensor 23 and the reflecting surface 7b is L, and the laser beam reflected by the reflecting surface 7b when the reflecting surface 7a is positioned at both ends of the rotation range ± θ (usually about 10 degrees). 24 incident positions E10 on the + θ side and E20 on the −θ side are obtained in advance. The distance between the center B of the optical sensor 25 and the beam splitter 22 is M.
[0017]
Then, in the same manner as in the prior art, drilling is performed at a predetermined position of the printed board 14 by the laser beam 12.
[0018]
When a predetermined time elapses, the controller 9 positions the reflecting surface 7 a at the reference position and causes the laser light source 21 to output the laser beam 24. First, the distance b from the center B0 of the position B1 where the laser beam 24 reflected by the beam splitter 22 of the optical sensor 25 enters is examined. When the distance b is not 0 and is within a predetermined range, the displacement angle α of the laser beam 24 is obtained as tan α = b / M, and the displacement angle α is stored. Next, the distance a from the center A0 of the position A1 where the laser beam 24 reflected by the reflecting surface 7b of the optical sensor 23 enters is examined. If the distance a is not 0 and is within a predetermined range, the displacement angle β of the reflecting surface 7b is obtained as tan2β = a / L, and the displacement angle β is stored. Then, a displacement amount γ (zero drift) of the laser beam 12 reflected by the reflecting surface 7a at the reference position is obtained from the displacement angle α and the displacement angle β.
[0019]
Next, the reflecting surface 7a is positioned at + θ of the rotation range, and after obtaining the distance e1 from the center A0 of the incident position E11 of the laser beam 24 reflected by the reflecting surface 7b, the reflecting surface 7b is set to −θ of the rotation range. The distance e2 from the center A0 of the incident position E21 of the laser beam 24 reflected by the reflecting surface 7b is obtained. Then, the displacement δ (scale drift) is obtained from the difference between the distance between E11 and E21, that is, the sum of the distance e1 and the distance e2 and the distance e0 between E10 and E20.
[0020]
Then, the positioning angle of the reflecting surface 7a when performing the subsequent processing is corrected based on the displacement amount γ and the displacement amount δ.
[0021]
In this embodiment, since the laser beam 24 is reflected by the reflecting surface 7b using the back side of the mirror 7 having a sufficient space, it is easy to sufficiently increase the distance L. In comparison, the resolution can be improved by about 10 times.
[0022]
Here, the effective length of the optical sensor 23 is, for example, about 30 mm when the resolution is 0.1 μm.
[0023]
Further, since the displacement angle α of the laser beam 24 is obtained, for example, when the holding portion of the laser light source 21 is displaced due to a temperature rise inside the laser light source 21 and the incident angle of the reflection surface 7b of the laser beam 24 is changed. However, the position of the reflecting surface 7a can be corrected with high accuracy.
[0024]
Since the mirror 7 is thick, the position of the reflecting surface 7a is actually corrected in consideration of the thickness of the mirror 7. In this case, since the thickness of the mirror 7 does not change and is a fixed value, it can be easily corrected.
[0025]
Further, the case where there is one mirror has been described above, but the present invention can also be applied to a case where two mirrors are used and the laser beam 12 is incident on the fθ lens 10 in the biaxial direction.
[0026]
Further, the laser beam 24 may be incident on the reflecting surface 7a.
[0027]
Further, in the above description, the displacement of the reflecting surface 7a is checked every predetermined time. However, since the displacement does not normally increase rapidly, the reflecting surface 7a is moved to the reference position or both end positions for processing. When positioning, the laser beam 24 is output to measure the displacement of the reflecting surface 7a, so that the displacement of the reflecting surface 7a can be obtained while processing.
[0028]
Further, in order to make the beam diameter and energy distribution of the laser light 24 uniform, an optical means such as a beam mode shaping unit or a focus lens may be disposed between the laser light source 21 and the beam splitter 22.
[0029]
Further, for example, an fθ lens may be disposed between the reflective surface 7b and the optical sensor 23 so that the laser beam 24 reflected by the reflective surface 7b is incident on the optical sensor 23 perpendicularly. By doing so, the diameter of the laser beam 24 incident on the optical sensor 23 becomes constant, and the positioning accuracy of the incident positions E10, E11, etc. can be further improved.
[0030]
Alternatively, a plurality of laser light sources 21 may be provided to detect displacements at a plurality of positions on the reflecting surface 7a.
[0031]
【The invention's effect】
As described above, according to the present invention, the laser processing apparatus that irradiates the laser beam oscillated from the laser oscillator onto the mirror that can be positioned around the axis and processes the workpiece with the laser beam reflected by the mirror. A beam irradiation device for irradiating a guide beam different from the laser beam used for processing and a light receiving device, and the light receiving device is opposite to the beam irradiation device with respect to an axis perpendicular to the reflecting surface of the mirror The guide beam is disposed at a position where it can receive light, and the rotation angle of the mirror is detected from the position of the guide beam received by the light receiving device. Therefore, if trial processing for confirmation is performed at the time of device assembly, the subsequent mirror position confirmation can be performed between processing, for example, in parallel with the replacement work of the printed circuit board, as in the conventional case. It is not necessary to confirm the position of the mirror by trial processing every time the position of the mirror is confirmed, and the confirmation can be performed in a short time, and the operating rate of the apparatus is improved. Further, the distance between the reflecting surface and the optical sensor can be increased, and the positioning accuracy of the reflecting surface can be improved.
[Brief description of the drawings]
FIG. 1 is an apparatus configuration diagram of a scanner placement unit in a laser drilling machine according to the present invention.
FIG. 2 is a diagram for explaining measurement specifications in the present invention.
FIG. 3 is an external view of a scanner arrangement portion in a conventional laser drilling machine.
FIG. 4 is a diagram illustrating zero drift and scale drift.
FIG. 5 is a diagram illustrating a conventional technique.
[Explanation of symbols]
7 Mirror 7
7a Reflecting surface 7b Reflecting surface 12 Laser light 21 Beam irradiation device 22 Beam splitter 23 Light receiving device 24 Guide beam

Claims (1)

In a laser processing apparatus that irradiates a laser that is oscillated from a laser oscillator onto a mirror that can be positioned around an axis, and processes a workpiece with the laser light reflected by the mirror, it is different from the laser light that is used for processing. A beam irradiation device for irradiating a laser beam and a first light receiving device are provided, and the laser beam from the beam irradiation device is directed toward a reflection surface on the back side of the reflection surface of the mirror parallel to the reflection surface of the mirror. irradiation, the first light receiving device, placed in the beam irradiation apparatus and the laser beam can be received a position opposite with respect to an axis perpendicular to the reflecting surface of the mirror, and received by the first light receiving device the from the position of the laser beam, detects the amount of rotational displacement of the mirror, also said together with the beam irradiation apparatus and providing a beam splitter between the lens, the light-receiving the reflected light from the beam splitter A second light receiving device is disposed at a position where the displacement of the beam irradiation device is detected from the position of the laser beam received by the second light receiving device, and the rotational displacement amount of the mirror and the beam irradiation device A laser processing apparatus that corrects a positioning angle of the mirror when performing processing based on a displacement amount of the mirror .

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