JP6449094B2 - Laser processing apparatus and laser processing method - Google Patents

Description

  The present invention relates to a laser processing apparatus and a laser processing method for making a hole in a printed circuit board using a laser, for example.

As a laser drilling method, there is a method in which a laser pulse output from a laser oscillator is branched by an acousto-optic modulator (hereinafter referred to as AOM) in synchronization with the stop of a galvano scanner and is irradiated onto a workpiece. In this method, the laser oscillation period changes based on the fluctuation of the hole interval , thereby causing a fluctuation of the thermal lens action in the AOM, resulting in a non-uniform shape of the hole and a deterioration of the processing quality.
In order to solve this problem, as disclosed in Patent Document 1, a technique for adjusting the pulse width so that the duty of the laser pulse becomes a predetermined ratio in accordance with the variation in the hole interval has been proposed. ing.

  However, the laser power of the laser oscillator depends on various conditions. For example, since the laser gas has a lifetime, there is a secular change such as a gradual drop in the laser power, and it cannot be determined simply by the duty alone. Therefore, the technique of Patent Document 1 has a drawback that the adverse effect due to the fluctuation of the thermal lens action in the AOM cannot be prevented.

JP 2004-358507 A

  In view of this, the present invention relates to a method in which a laser pulse output from a laser oscillator is branched by an AOM and irradiated to a workpiece in synchronization with the stop of the galvano scanner. The purpose is to prevent adverse effects due to fluctuations in the quality and improve the processing quality.

  In order to solve the above-described problem, in the laser processing apparatus according to claim 1, a laser oscillator that oscillates a laser pulse for each processing position of a workpiece and a laser pulse output from the laser oscillator in a non-processing direction. In a laser processing apparatus having an acoustooptic modulator that branches in two processing directions, a power detector that detects a laser power of the laser oscillator, and a processing position based on processing data for processing the workpiece. A processing order determination unit that determines the order; a power recording unit that records detection data of the power detector when the laser oscillator is oscillated in the order of the processing positions at a time point before processing the workpiece; Output from the laser oscillator based on data recorded in the power recording unit at the time of processing the workpiece. A laser pulse width control unit for controlling the pulse width of the laser pulse, and the laser pulse width control unit delays the rear end of the laser pulse and increases the pulse width when the interval between the processing positions becomes large. Features.

  Further, in the laser processing method according to claim 2, the laser pulse oscillated by the laser oscillator for each processing position of the workpiece is input to an acousto-optic modulator that branches in two ways, a processing direction and a non-processing direction. In the laser processing method of irradiating the processing position on the workpiece with the laser pulse branched in the processing direction in the acousto-optic modulator, the workpiece is processed before the processing of the workpiece. And determining the order of processing positions based on the processing data for recording, recording laser power when the laser oscillator is oscillated in the order of the processing positions, and recording data at the time of processing the workpiece Based on the above, the pulse width of the laser pulse output from the laser oscillator is controlled. Cast was characterized by increasing the pulse width.

  According to the present invention, in a system in which a laser pulse output from a laser oscillator is branched by an AOM in synchronization with the stop of a galvano scanner and irradiated to a workpiece, a thermal lens in the AOM in consideration of the secular change of the laser oscillator It is possible to prevent adverse effects due to fluctuations in action.

It is a block diagram of the laser drilling apparatus which becomes one Example of this invention. It is a figure for demonstrating the change of the laser power recorded on the power recording part in FIG. It is a figure for demonstrating operation | movement of the laser pulse width control part in FIG. It is a timing chart of the laser drilling apparatus which becomes one Example of this invention.

  An embodiment of the present invention will be described. FIG. 1 is a block diagram of a laser drilling apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a printed board to be processed placed on a table (not shown), 2 is a laser oscillator that oscillates a laser pulse L1, and 3 is a laser pulse L1 output from the laser oscillator 2 with a power ratio of 99%. A beam splitter that distributes to 1%, AOM splits the laser pulse L1 distributed by the beam spiriter 3 at a power ratio of 99% in two ways, a machining direction and a non-machining direction, and AOM 4 branches in the machining direction at AOM4. It is a galvano scanner that scans the laser pulse L2 and sequentially irradiates the punched position of the printed circuit board 1. The galvano scanner 5 rotates to scan the laser pulse L2. A damper 6 absorbs the laser pulse L3 branched in the non-machining direction in the AOM4. Reference numeral 7 denotes a power detector that detects the laser power of the laser pulse L1 distributed by the beam spiriter 3 with a power ratio of 1%.

Reference numeral 9 denotes an overall control unit for controlling the operation of the entire apparatus, which is realized by, for example, a program control processing apparatus. The overall control unit 9 outputs a laser oscillation command signal S that instructs the laser oscillator 2 to oscillate a laser pulse L1, and an AOM control unit that outputs an AOM drive signal D that controls the branching operation of the AOM 4. 11. Galvano control unit 12 that outputs a galvano operation control signal G for instructing the operation of the galvano scanner 5, a processing order determination unit 13 that determines the processing order of each hole based on the processing data stored therein, and each hole position A power recording unit 14 that records the laser power value detected by the power detector 7 at the time, and a laser oscillation stop command signal N at each hole position time point based on the laser power value at each hole position time point recorded in the power recording unit 14 And a laser pulse width control unit 15 for adjusting the pulse width at that time. Some of these functional elements included in the overall control unit 9 may be provided separately from the overall control unit 9.
The laser drilling device has various elements and connection lines other than those described here, but is omitted here.

The galvano operation control signal G stops the galvano scanner 5 in the off time zone and rotates the galvano scanner 5 in the on time zone. One hole is drilled while the galvano scanner 5 is stationary, and the galvano scanner 5 rotates to irradiate the next hole position with the laser pulse L2.
The laser oscillation command signal S causes the laser oscillator 2 to oscillate when turned on, and stops the oscillation when turned off.
The laser oscillation command signal S is turned on in synchronization with the galvano operation control signal G being turned off, and the galvano operation control signal G is turned on with a certain delay from the laser oscillation command signal S being turned on. Rotate.
The AOM drive signal D is divided into a laser pulse L2 by dividing the laser pulse L1 input to the AOM 4 only in the time zone when the AOM drive signal D is on. Branch in the direction of the damper 6.

  The operation of this apparatus is divided into a pre-processing stage in which processing is not actually performed on the printed circuit board 1 and a processing stage in which processing is actually performed on the printed circuit board 1. To work.

  In the pre-processing stage, the laser oscillator 2 oscillates at each hole position time point according to the determination of the processing order determination unit 13, but the laser power value detected by the power detector 7 at every hole position time point is the power recording unit 14. To record. At this time, the AOM control unit 11 always turns off the AOM drive signal D, and branches the laser pulse L1 from the laser oscillator 2 in the direction of the damper 6 as a laser pulse L3 in the non-machining direction.

  FIG. 2 is a diagram for explaining a change in the laser power recorded in the power recording unit 14 and shows a case of the cycle machining in which the hole position is moved while irradiating one laser pulse at each hole position. It is. The laser power of the laser oscillator 2 is large at the hole positions N to N + 3 where the hole interval is small, and is small at the hole positions N + 4 to N + 6 where the hole interval is large. The power recording unit 14 records the laser power values as described above at all hole positions.

Next, in the processing stage, the laser oscillator 2 oscillates at each hole position time point according to the processing order determined by the processing order determination unit 13, but the laser pulse width control unit 15 detects each hole recorded in the power recording unit 14. The laser power value at each position time point is read, and the laser oscillation control unit 10 is controlled based on the read laser power value to adjust the on period of the laser oscillation command signal S at each hole position time point.
That is, the laser pulse width control unit 15 has the smallest hole interval at the hole positions N to N + 3, and when the hole interval becomes large like the hole positions N + 4 to N + 6, as shown in FIG. If the pulse width at W is W1, the pulse width is set to W2 and W3 larger than W1 at the hole positions N + 4 to N + 6 so that the drop in laser power can be compensated. As to W2 and W3, how much should be increased is obtained in advance by experiments or the like. By doing so, it is possible to prevent a drop in the laser power of the laser oscillator 2 at the hole positions N + 4 to N + 6, as indicated by the dotted line LP in FIG.

FIG. 4 is a timing chart of a laser drilling apparatus according to an embodiment of the present invention, and shows a case of cycle processing in which a hole position is moved while irradiating one laser pulse at each hole position. .
When the hole interval M + 1 is the smallest interval and the hole interval is large at the hole position M + 2, the laser oscillation command signal S is turned on in synchronization with the galvano operation control signal G being turned off. Is extended as indicated by the dotted line, and accordingly, the rear end of the laser pulse L1 is delayed to increase the pulse width.
In this case, the AOM drive signal D is not changed, and the pulse width of the laser pulse L2, which is a machining pulse, is not changed.

Although the case of the cycle machining has been described above, the present invention can also be applied to a burst machining in which a plurality of laser pulses are continuously irradiated for each hole position and then moved to an adjacent hole position.
That is, in the burst processing, the galvano scanner 5 stops at every hole position and the laser oscillator 2 oscillates a plurality of times at a predetermined cycle. In the stage before processing, the laser power value based on such a cycle is obtained. Is recorded in the power recording unit 14, the pulse width of the laser pulse can be adjusted in the processing stage according to the data of the power recording unit 14 as in the case of the cycle processing.

  According to the above embodiment, the relationship between the laser power of the laser oscillator 2 actually used for processing and the hole position interval is grasped in the pre-processing stage, and the laser pulse width is adjusted in the processing stage based on the result. Therefore, the change of the laser power can be suppressed as much as possible in consideration of the secular change of the laser oscillator 2. Accordingly, it is possible to prevent the adverse effect caused by the variation of the thermal lens action in the AOM 4 as accurately as possible and improve the processing quality.

In the above embodiment, the laser power value detected by the power detector 7 at each hole position time point in the pre-processing stage is recorded in the power recording unit 14. However, when it is known in advance that the change in the interval between the individual hole positions is not large and the fluctuation of the laser power of the laser oscillator 2 is small, the power recording unit 14 stores all the hole position points in the pre-processing stage. Instead, the laser power value may be recorded at every several hole positions, and the laser pulse width may be adjusted only at the hole position at the processing stage.
Furthermore, even if the laser power of the laser oscillator 2 changes, if an allowable range can be set, the laser power that does not reach the predetermined level in the power recording unit 14 at the time of all hole positions in the pre-processing stage. It is also possible to record only the time of the hole position where the value is reached and adjust the laser pulse width only at the time of the hole position in the processing stage.

  Further, in the above-described embodiment, the embodiment in the case where the printed circuit board is punched has been described. However, the present invention can be provided for laser processing in which processing is sequentially performed on a plurality of portions of the workpiece.

1: printed circuit board, 2: laser oscillator, 3: beam spirit, 4: AOM
5: Galvano scanner, 6: Damper, 7: Power detector, 9: Overall control unit 10: Laser oscillation control unit, 11: AOM control unit, 12: Galvano control unit 13: Processing order determination unit, 14: Power recording unit, 15: Laser pulse width controller L1 to L3: Laser pulse, S: Laser oscillation command signal, G: Galvano operation control signal D: AOM drive signal

Claims (2)

  In a laser processing apparatus having a laser oscillator that oscillates a laser pulse for each processing position of a workpiece, and an acousto-optic modulator that branches a laser pulse output from the laser oscillator in two directions, a processing direction and a non-processing direction A power detector for detecting the laser power of the laser oscillator, a processing order determining unit for determining the order of processing positions based on processing data for processing the workpiece, and before processing the workpiece A power recording unit that records detection data of the power detector when the laser oscillator is oscillated in the order of the processing positions at the time, and data recorded in the power recording unit at the time of processing the workpiece And a laser pulse width controller for controlling the pulse width of the laser pulse output from the laser oscillator based on The laser processing apparatus the laser pulse width control unit, characterized in that increasing the pulse width by delaying the trailing edge of the laser pulse when the interval between the processing position has increased.   A laser pulse oscillated by a laser oscillator for each processing position of a workpiece is input to an acousto-optic modulator that branches in two directions, a processing direction and a non-processing direction, and the laser is branched in the processing direction in the acousto-optic modulator. In a laser processing method for irradiating a processing position on a workpiece with a pulse, a processing position order is determined based on processing data for processing the workpiece before processing the workpiece. In addition, laser power when the laser oscillator is oscillated in the order of the processing positions is recorded, and a pulse of a laser pulse output from the laser oscillator based on the recording data at the time of processing the workpiece The width is controlled and the trailing edge of the laser pulse is delayed to increase the pulse width when the processing position interval increases. The processing method.

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