JP7510380B2 - Laser Processing Equipment - Google Patents

Description

The present invention relates to a laser processing device.

Conventionally, a laser processing device has been proposed that includes an acousto-optic modulator that can distribute the laser pulses emitted from a laser oscillator to a processing direction and a non-processing direction, and that uses this acousto-optic modulator to extract a portion of the laser pulses emitted from the laser oscillator as laser pulses for processing (see Patent Document 1).

JP 2019-025505 A

When an acousto-optic modulator is used, as in the laser processing device described in Patent Document 1, a desired portion of the laser pulses emitted from the laser oscillator can be used as the processing laser beam. However, in Patent Document 1, the laser pulse is extracted by outputting a drive signal for the acousto-optic modulator a predetermined time after a laser oscillation command signal that commands the oscillation and attenuation of the laser pulse in the laser oscillator is output.

The time from when the laser oscillation command signal is output until the laser pulse is emitted from the laser oscillator (the time until the laser pulse rises) varies depending on the laser pulse. In addition, the intensity of the laser pulse emitted from the laser oscillator varies over time, for example, exponentially increasing with time from the start of the rise and exponentially decreasing as the oscillation command signal stops. For this reason, if there is variation in the time until the laser pulse rises, there is a risk that the intensity will vary in the extracted laser pulse, and the quality of the hole drilled in the substrate will deteriorate.

Therefore, the present invention aims to provide a laser processing device with high processing accuracy.

One aspect of the present invention is a laser processing device that includes a laser oscillator, a deflection means capable of deflecting a laser pulse emitted from the laser oscillator toward a processing path, and a control means that outputs an oscillation command signal to emit a laser pulse from the laser oscillator and controls the deflection means to cut out a part of the laser pulse emitted from the laser oscillator toward the processing path, and is characterized in that, when a second laser pulse is emitted from the laser oscillator immediately after a first laser pulse, the oscillation command signal output from the control means to the laser oscillator during the period from when the oscillation command signal for the first laser pulse is output to when the first laser pulse is emitted is set to a first oscillation command signal, and the oscillation command signal output from the control means to the laser oscillator during the period from when the oscillation command signal for the second laser pulse is output to when the second laser pulse rises is set to a second oscillation command signal, the intensity of the second oscillation command signal is made greater than the intensity of the first oscillation command signal.

The present invention provides a laser processing device with high processing accuracy.

1 is a schematic diagram of a laser processing apparatus according to an embodiment of the present invention. 4 is a time chart showing the relationship between a pulse laser and an oscillation command according to the embodiment. FIG. 13 is a diagram showing a model illustrating the relationship between an oscillation interval, an oscillation time, and a correction value for the intensity of an oscillation command signal. FIG. 4 is a flowchart showing an operation of correcting the intensity of an oscillation command signal.

The laser processing device and the laser processing method according to the embodiment of the present invention will be described below with reference to the drawings. Note that in the following description, the X-axis direction and the Y-axis direction are based on the state when the processing object is viewed in a plan view.

<General configuration of laser processing device>
As shown in FIG. 1, the laser processing apparatus 1 according to this embodiment is a laser processing apparatus that performs hole drilling on a printed circuit board W as a processing object placed on a processing table 2 that is movable in the XY axis directions, and in addition to the processing table 2 described above, it is equipped with a laser oscillator 3, an acousto-optical device (hereinafter referred to as AOD) 4, a beam damper 5, a scanning unit 6, a focusing (Fθ) lens 7, a control unit (control means) 10, etc.

The laser oscillator 3 is, for example, a carbon dioxide (CO ₂ ) laser oscillator, and the generated laser is emitted from the laser oscillator 3 as a laser pulse (pulse laser) L1.

The AOD4 is an extraction means for extracting a laser pulse for processing from the laser pulse L1 emitted from the laser oscillator 3, and functions as a distribution means (route selection means) for distributing the laser pulse L1 to either the damper route or the processing route. When not in operation, the laser beam incident on the AOD4 passes through the AOD4 as zeroth-order diffracted light and is emitted to the above-mentioned damper route (laser pulse L3). When in operation, the laser beam is emitted from the AOD4 as first-order diffracted light to the above-mentioned processing route (laser pulse L2).

The scanning unit 6 is disposed downstream of the AOD 4 on the optical path of the laser beam, and includes a first galvanometer scanner that scans the processing laser pulse L2 in the X-axis direction, and a second galvanometer scanner that scans in the Y-axis direction. The processing laser pulse L2 is positioned at an irradiation position in the X-axis and Y-axis directions on the printed circuit board W by the pair of galvanometer scanners of the scanning unit 6.

The control unit 10 of the laser processing device 1 is an overall control unit that controls the entire laser processing device 1, and includes a laser oscillation control unit 11, an AOD control unit 12, a galvanometer control unit 13, etc. The laser oscillation control unit 11 outputs an oscillation command signal S1 to the laser oscillator 3 to command the oscillation and attenuation of the laser beam in the laser oscillator 3, and controls the intensity and pulse width of the laser pulse L1 emitted from the laser oscillator 3. The AOD control unit 12 outputs an AOD drive signal S2 to the AOD 4, and controls the timing of cutting out the laser pulse L2 for processing. The galvanometer control unit 13 outputs a galvanometer control signal S3 to the scanning unit 6, and controls the rotation angle of the mirror of the galvanometer scanner.

For this reason, when the laser processing device 1 irradiates a laser pulse to a predetermined position on a printed circuit board W to perform hole drilling, for example, a galvanometer control signal S3 is output from the galvanometer control unit 13 to the galvanometer scanner of the scanning unit 6 in accordance with the processing position on the printed circuit board W, and the laser irradiation position is positioned.

When positioning by the scanning unit 6 is completed, the laser oscillation control unit 11 outputs an oscillation command signal S1, and the laser oscillator 3 emits a laser pulse L1 with a laser intensity and pulse width according to the oscillation command signal S1 toward the AOD 4.

The laser pulse L1 is shaped by an optical processing section consisting of a collimator, an aperture, etc., and then enters the AOD4. At this time, since the AOD4 is not driven, the incident laser pulse L1 is not deflected by the AOD4, and is emitted as it is to the damper path as a laser pulse L3. The laser pulse L3 is absorbed by the beam damper 5.

When a predetermined time has elapsed since the output of the oscillation command signal S1, the AOD control unit 12 outputs the AOD drive signal S2, and the AOD 4 is driven. When the AOD 4 is driven, the laser pulse L1 is deflected and its optical path is switched to the processing path. As a result, a part of the laser pulse L1 is extracted as a laser pulse L2 for processing, and is incident on the scanning unit 6. The laser pulse L2 incident on the scanning unit 6 is deflected in the XY axis direction by the first and second galvano scanners, and is incident on the focusing lens 7. It is then focused at a predetermined position on the printed circuit board W, and a hole is drilled in the printed circuit board W.

The above-mentioned laser oscillation control unit 11, AOD control unit 12, and galvano control unit 13 may each be realized as a function (process) of the control program of the laser processing device 1, or may be realized as an independent circuit. For this reason, the control unit 10 has at least one memory unit in which the above-mentioned control program is stored, and at least one CPU (calculation unit) that executes the control program.

<Laser cutting operation>
Next, the laser pulse cutting operation by the AOD 4 described above will be explained. Figure 2 shows the pulse laser L1 emitted from the laser oscillator 3, and shows the first laser pulse P1 and the second laser pulse P2 emitted consecutively. As shown in the first laser pulse P1, even if the oscillation command signal S1 is output, the laser pulse does not rise immediately, and there is a predetermined delay time d1 between the time t1 when the oscillation command signal S1 is turned on and the time when the laser pulse P1 is actually emitted (rises) (time t2). In addition, the laser pulse P1 rises exponentially from the time t2, and when the oscillation time tb has passed and the oscillation command signal S1 is turned off (time t3), it decays exponentially and eventually becomes zero.

Similarly, the second laser pulse P2 also rises after a delay time has elapsed since the oscillation command signal S1 was turned on. However, when laser pulses are output consecutively, even if the intensity and oscillation time of the oscillation command signal S1 are the same, the delay time may be longer due to the influence of the previous laser pulse. For example, when the oscillation command signal S1 has the same intensity (rated) and oscillation time (tb = tc) as the first laser pulse, as shown by the dotted line, the second laser pulse P2 rises (at time t6) after the oscillation command signal S1 is turned on (at time t4), and after the delay time d1 (at times t4 to t5) and the variable delay time d2 (at times t5 to t6) have elapsed.

In this way, if the time from when the oscillation command signal S1 is turned on until the laser pulse rises differs between the first and second pulses, the intensity of the extracted laser pulse will vary because the AOD4 extracts the laser pulse based on the output of the oscillation command signal S1. For this reason, in this embodiment, the time until the laser pulse rises is shortened by correcting the intensity of the oscillation command signal S1.

Specifically, for the second laser pulse P2 (solid line) in FIG. 2, during the delay time d1 (times t4 to t5), the oscillation command strength of the oscillation command signal S1 is increased from the rated strength by strength C. As a result, the rising edge of the laser pulse is advanced by the variable delay time d2, as in the second laser pulse P2 shown by the solid line (the pulse is delayed by the variable delay time d2).

More specifically, the variable delay time varies depending on the oscillation interval (the interval from when the oscillation command signal S1 of the previous laser pulse is turned on until the oscillation command signal S1 of the laser pulse is turned on) and the oscillation time of the previous laser pulse (the time during which the oscillation command signal S1 is on). Specifically, taking the second laser pulse P2 as an example, the variable delay time d2 varies depending on the oscillation interval Tb and the oscillation time tb.

As shown in FIG. 3, the control unit 10 of the laser processing device 1 stores in the memory unit a model showing the relationship between the oscillation interval, the oscillation time, and the correction value C of the intensity of the oscillation command signal S1. Note that in FIG. 3, T1 to Tn are the oscillation interval of the oscillation command signal S, t1 to tn are the oscillation time of the oscillation command signal S1, and C11 to Cnn are the intensity correction values of the oscillation command.

The above model is obtained in advance by experiment. In this model, the larger the order of the oscillation interval and the oscillation time, the larger the values of the oscillation interval and the oscillation time. Also, for the same oscillation interval, the longer the oscillation time, the larger the value of (delay time d1 + variable delay time d2), and therefore the larger the value of the correction value C of the intensity of the oscillation command signal S1. Also, for the same oscillation time, the shorter the oscillation interval, the larger the value of (delay time d1 + variable delay time d2), and therefore the larger the value of the correction value C of the intensity of the oscillation command signal S1. Also, in the range where the variable delay time d2 does not exist or can be ignored, the intensity of the oscillation command signal S1 is not corrected. In other words, when the estimated delay time is equal to or greater than a predetermined threshold, the intensity of the oscillation command signal S1 is corrected.

When the intensity of the oscillation command signal S1 increases, in the case of the first laser pulse P1 and the second laser pulse P2 (solid line) in Figure 2, the rise of the second laser pulse P2 becomes faster.

Next, a method for setting the correction value for the intensity of the oscillation command signal S1 will be described with reference to FIG. 4. When a command to process a printed circuit board is input, the control unit 10 acquires the oscillation intervals and oscillation times of all laser pulses used to process each hole in the printed circuit board W (step S1 in FIG. 4). Then, based on the acquired oscillation intervals and oscillation times of the laser pulses, the control unit 10 refers to the model for each laser pulse and determines whether or not it is necessary to set a correction value C for the oscillation command signal S1 (S2 in FIG. 4).

For the oscillation command signal S1 of the laser pulse that requires the setting of a correction value C, the correction value C is set according to the oscillation interval and oscillation time (S3 in FIG. 4). For the oscillation command signal S1 that does not require the setting of a correction value C, the rated value is set as the intensity value of the oscillation command signal S1. Then, when the setting of the oscillation command signal S1 for all the laser pulses is completed, the drilling process of the printed circuit board is started.

<Summary>
The laser processing apparatus (1) according to the present embodiment is
A laser oscillator (3);
a deflection means (4) capable of deflecting a laser pulse (L1) emitted from the laser oscillator (3) toward a processing path;
a control means (10) for outputting an oscillation command signal (S1) to cause the laser oscillator (3) to emit a laser pulse (L1) and for controlling the deflection means (4) to cut out a part of the laser pulse emitted from the laser oscillator (3) toward the processing path;
In the case where a second laser pulse (P2) is emitted from the laser oscillator (3) successively to a first laser pulse (P1),
the oscillation command signal (S1) output from the control means (10) to the laser oscillator (3) during the period (t1 to t2) from when the oscillation command signal (S1) for the first laser pulse (P1) is output until the first laser pulse (P1) is emitted is defined as a first oscillation command signal;
When the oscillation command signal (S1) output from the control means (10) to the laser oscillator (3) during the period from when the oscillation command signal (S1) for the second laser pulse (P2) is output until the second laser pulse (P2) rises (t4 to t5), the oscillation command signal (S1) is set as a second oscillation command signal,
The intensity of the second oscillation command signal is set to be greater than the intensity of the first oscillation command signal.

By making the intensity of the second oscillation command signal larger (stronger) than the intensity of the first oscillation command signal in this way, the variable delay time d2 of the second laser pulse P2 can be reduced. This reduces the variation in the intensity of the laser pulse that occurs when the laser pulse is extracted for processing, and improves the processing quality of the hole.

More specifically, the intensity of the second oscillation command signal varies according to the oscillation interval from when the oscillation command signal for the first laser pulse is output to when the oscillation command signal for the second laser pulse is output.

Furthermore, the intensity of the second oscillation command signal varies depending on the oscillation time during which the oscillation command signal for the first laser pulse is output.

The control means (10) also drives the deflection means (4) after a predetermined time has elapsed since the oscillation command signal (S1) was output, to cut out a portion of the laser pulse (L1) toward the processing path.

By correcting the intensity value of the second oscillation command signal according to the oscillation interval and oscillation time, the laser pulse can be appropriately corrected according to the characteristics of the hole to be machined, thereby improving the quality of the hole.

In the above embodiment, the AOD4 is used as an example of the deflection means, but this is not limiting, and an electro-optical modulator (EOM), for example, may also be used.

1: Laser processing device 3: Laser oscillator 4: Deflection means (AOD)
10: Control means P1: First laser pulse P2: Second laser pulse L1: Laser pulse S1: Oscillation command signal

Claims (4)

A laser oscillator;
A deflection means capable of deflecting a laser pulse emitted from the laser oscillator toward a processing path;
a control means for outputting an oscillation command signal to cause the laser oscillator to emit a laser pulse and for controlling the deflection means to cut out a part of the laser pulse emitted from the laser oscillator toward the processing path;
When a second laser pulse is emitted from the laser oscillator successively to a first laser pulse,
an oscillation command signal output from the control means to the laser oscillator during a period from when an oscillation command signal for the first laser pulse is output until the first laser pulse is emitted is defined as a first oscillation command signal;
When the oscillation command signal output from the control means to the laser oscillator during the period from when the oscillation command signal for the second laser pulse is output until the second laser pulse rises is set as a second oscillation command signal,
The intensity of the second oscillation command signal is made greater than the intensity of the first oscillation command signal.
A laser processing device characterized by: an intensity of the second oscillation command signal varies according to an oscillation interval from when an oscillation command signal for the first laser pulse is output to when an oscillation command signal for the second laser pulse is output;
2. The laser processing apparatus according to claim 1. The intensity of the second oscillation command signal varies depending on an oscillation time during which the oscillation command signal for the first laser pulse is output.
3. The laser processing apparatus according to claim 1 or 2. The control means drives the deflection means after a predetermined time has elapsed since an oscillation command signal was output, and cuts out a part of the laser pulse toward the processing path.
4. The laser processing apparatus according to claim 1, wherein the laser processing apparatus is a laser processing apparatus having a laser beam.

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