JP4049459B2 - Laser processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is applied to general high-speed positioning control using a galvanometer. In particular, the present invention relates to a laser hole machining method that requires high-speed positioning of a galvanometer, and more particularly to a method of machining a hole by irradiating a circuit board or the like with a laser via a mirror attached to the galvanometer.
[0002]
[Prior art]
A laser hole machining technique using a galvanometer mirror is adopted in an operation for machining a hole such as a through hole in a circuit board with high-density wiring.
[0003]
Laser drilling technology is a method of irradiating a workpiece with a laser beam and melting or evaporating the workpiece with the energy of the laser beam to form a hole. Suitable for cases. The number of holes processed per unit area in circuit boards with high-density wiring, which is representative of recent electronic devices such as mobile phones, is increasing more and more due to finer holes and higher board density. In order for the laser drilling technology to be widely used in the manufacture of substrates, it is essential to increase the speed of drilling.
[0004]
As a specific example of a hole processing technique using a galvanometer mirror in which a mirror is attached to a galvanometer, a laser beam is galvanometered as disclosed in Japanese Patent Application Laid-Open No. Hei 8-174256 and the like previously filed by the present applicant. Laser processing is performed by reflecting the light with a mirror, condensing with a condensing lens, and irradiating the circuit board to be processed.
[0005]
The galvanometer used in such hole drilling technology has a high resolution on the order of μrad, and has a drive region with an optical angle of ± 20 ° and a high-speed positioning characteristic. Positioning is performed by analog feedback control of the servo system provided as detection means.
[0006]
Specifically, when a movement command for the galvanometer is given from the control unit, as shown in FIG. 4, the actual rotational movement angle is controlled so as not to exceed the target rotational angle, and gradually approaches the target rotational angle. In this way, the galvanometer is controlled to rotate, and when the target rotation angle is reached and stabilized, a laser beam irradiation command is issued to perform laser processing.
[0007]
Here, Mv in FIG. 4 is a movement time in which the target rotation angle is varied as a movement command for the galvanometer mirror, Jd is a positioning time until the galvanometer mirror is subsequently moved to the target rotation angle, and Lon is a laser. The light irradiation time, Sd, is the laser wave tail waiting time.
[0008]
Note that the capacitance sensor that detects the position of the galvanometer mirror is output as a minute analog signal and is difficult to use for determining target positioning completion due to the influence of noise, etc. A fixed waiting time is set as the positioning time Jd from the time when movement of the movement command to the galvano mirror in the feedback control ends (end point of the moving time Mv), and it is considered that the positioning is completed when the positioning time Jd elapses. The laser beam irradiation is started after the determination and the positioning is completed. As the positioning time Jd, a longer time is set assuming a worst case where the rotational movement angle of the galvano mirror is large and takes a long time.
[0009]
[Problems to be solved by the invention]
However, when the galvanometer mirror is controlled as described above, it is considered that the positioning is completed after waiting for a long time regardless of the rotational movement angle of the galvanometer mirror. It takes a long time, and the processing tact per workpiece cannot be shortened, resulting in a problem that the processing capacity does not increase and productivity does not improve.
[0010]
SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to provide a laser processing method that can shorten the processing tact per workpiece and improves the productivity.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention rotates a galvano mirror according to a movement command, detects a rotation angle of the galvano mirror, detects an angle difference between the detected rotation angle and a target rotation angle, and detects the detected Based on the angle difference, the galvano mirror is positioned at a target rotation angle, and after a set waiting time corresponding to the movement angle of the galvano mirror from the movement command, the galvano mirror is irradiated with a laser beam and reflected by the galvano mirror. A laser processing method for performing laser processing by condensing the laser beam with a condensing lens and irradiating the workpiece, wherein the setting waiting time is smaller as the movement angle of the galvanometer mirror is smaller. To do.
[0012]
By this method, it is possible to shorten the processing tact per one workpiece, and the productivity is improved.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention rotates a galvano mirror according to a movement command, detects a rotation angle of the galvano mirror, detects an angle difference between the detected rotation angle and a target rotation angle, and based on the detected angle difference, the galvano mirror Is positioned at a target rotation angle, and after a set waiting time corresponding to the movement angle of the galvano mirror from the movement command, the galvano mirror is irradiated with a laser beam, and the laser beam reflected by the galvano mirror is reflected on the condenser lens. Is a laser processing method for performing laser processing by condensing and irradiating a workpiece, and the smaller the movement angle of the galvanometer mirror, the shorter the set waiting time .
[0014]
According to the above method, since the set waiting time can be reduced when the movement angle of the galvano mirror is small, the machining tact per workpiece can be shortened, and the productivity is improved. .
[0015]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a case where the present invention is used in a laser processing apparatus that processes holes such as through holes in a circuit board having high-density wiring will be described.
[0016]
As shown in FIG. 1, the laser processing apparatus includes a laser oscillator 2 that emits a laser beam 1, a beam splitter 3 that splits the laser beam 1, a galvanometer mirror 4 in which a mirror 4b is attached to a galvanometer 4a, and a laser. Basically, an Fθ lens 5 as a condensing lens that condenses the light beam 1 on a plane and an XY table 7 that is movable in the X-axis direction and the Y-axis direction and on which a circuit board as a workpiece 6 is placed. It is configured.
[0017]
After the XY table 7 is positioned at the command position and the galvanometer mirror 4 is positioned at the command position to complete a hole at an arbitrary position of the workpiece 6 placed on the XY table 7, A laser beam 1 is irradiated from a laser oscillator 2 to perform hole machining. By positioning the galvanometer mirror 4, a hole can be drilled at an arbitrary point in an area of 50 mm × 50 mm, and the XY table 7 can be moved in units of 50 mm to process an arbitrary position on the workpiece 6 of 500 mm × 350 mm. It is configured.
[0018]
In the laser processing apparatus shown in FIG. 1, the laser beam is split by the beam splitter 3, two pairs of galvanometer mirrors 4 and an Fθ lens 5 are arranged, and two pairs of workpieces 6 are placed on an XY table 7. The simultaneous machining of the two workpieces 6 is realized by placing them.
[0019]
By the way, circuit boards with high-density wiring, which are representative of recent electronic devices such as mobile phones, have 1000 holes per 50 mm × 50 mm due to finer holes and higher circuit board density. In this case, the number of holes exceeds 50,000 holes, and the positioning time of the galvanometer mirror 4 greatly affects the tact of one workpiece.
[0020]
FIG. 2 shows a control system related to the galvanometer mirror 4. As shown in FIG. 2, the difference between the actual rotational movement angle of the galvanometer mirror 4 detected by the capacitance sensor 9 as the position detection means and the target rotation angle of the galvanometer mirror 4 functions as an angle difference detection unit. While calculating by the galvano driver 8, feedback control is performed based on this difference to move the galvano mirror 4 so as to approach the target rotation angle, and the galvano mirror after a set waiting time from the movement command from the host controller 10 as the control unit. The positioning of the laser beam is performed after the positioning is completed, and the laser beam is irradiated.
[0021]
In this case, according to the present invention, the set waiting time is set according to the movement angle of the galvanometer mirror 4 as shown in FIGS. Specifically, as shown in FIG. 3B, the positioning time Jd, which is the set waiting time, is set to decrease as the movement angle (movement distance) of the galvano mirror 4 decreases.
[0022]
In FIGS. 3A and 3B, Mv is a movement time during which the target rotation angle is changed as a movement command for the galvanometer mirror 4, and Jd is positioned after the galvanometer mirror 4 is moved to the target rotation angle. The positioning time until the start, Lon is the laser beam irradiation time, and Sd is the laser wave tail waiting time.
[0023]
As a result, in the prior art, even when the movement angle of the galvano mirror 4 is small, it is considered that the positioning has been completed after always waiting for a long time, so that the positioning of the galvano mirror 4 took a relatively long time. However, according to this control method, when the movement angle of the galvano mirror 4 is small, the positioning time Jd, which is a set waiting time, can be reduced, so that the machining tact per workpiece can be shortened. Is possible and productivity is improved.
[0024]
【The invention's effect】
As described above, according to the present invention, when the moving angle of the galvano mirror is small, the set waiting time can be reduced, so that the loss time in the control method based on time management is eliminated, and one workpiece is processed. This makes it possible to shorten the machining tact time and improve productivity.
[Brief description of the drawings]
FIG. 1 is a perspective view of a laser processing apparatus for performing a laser processing method according to an embodiment of the present invention. FIG. 2 is a diagram showing a galvanomirror control system of the laser processing apparatus. 4A and 4B are diagrams conceptually showing the laser processing method, wherein FIG. 4A shows a case where the moving distance of the galvano mirror is large, and FIG. 4B shows a case where the moving distance is small. Diagram conceptually [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser beam 2 Laser oscillator 4 Galvanometer mirror 4a Galvanometer 4b Mirror 5 F (theta) lens (condensing lens)
6 XY table 7 Work piece 8 Galvano driver 9 Capacitance sensor (position detection means)
10 Host controller (control unit)

Claims (1)

The galvano mirror is rotated by a movement command, the rotation angle of the galvano mirror is detected, the angle difference between the detected rotation angle and the target rotation angle is detected, and the galvano mirror is rotated based on the detected angle difference. After the set waiting time corresponding to the moving angle of the galvano mirror from the movement command, the galvano mirror is irradiated with a laser beam, and the laser beam reflected by the galvano mirror is condensed by a condenser lens. A laser processing method for performing laser processing by irradiating a workpiece, wherein the set waiting time is smaller as the movement angle of the galvanometer mirror is smaller .

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