JPH04313476A - Laser hole processing method - Google Patents

Abstract

PURPOSE:To offer the laser hole method which can improve surely the efficiency for hole working, and also, does not cause deterioration of the hole quality. CONSTITUTION:In the laser hole machining method for executing successively performation working plural objects to be worked 15A-15D installed on plural working optical axes 17A-17D by radiating a laser beam oscillated pulsatively by switching successively to plural, working optical axes 17A-17D by synchronizing with the time of non-excitation of this laser beam, whenever perforation of one hole to one object to be worked (one of 15A-15D) is completed, the laser beam is switched successively to other working optical axis.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser hole processing method for drilling holes such as through holes on a printed circuit board using a laser.

0002

2. Description of the Related Art Conventionally, a mechanical processing method using a drill has generally been used for drilling holes such as through-holes in printed circuit boards for mounting electronic components. However, in recent years, laser processing methods have been researched and developed in order to meet the need for smaller diameter holes and non-through hole processing as printed circuit board patterns become more dense. This type of technology has already been disclosed, for example, in JP-A-61-95792 and JP-A-62.
-216297. In order to further shorten the processing time in such conventional technology, as disclosed in Japanese Patent Application Laid-Open No. 2-187291, a plurality of semi-transmissive mirrors for beam splitting with different reflectances are used.
A method has also been proposed in which one laser beam is distributed to a plurality of optical axes for processing. In order to make drilling technology using laser beams practical from a cost perspective, it is necessary to improve efficiency, and in this respect, as mentioned above, multiple laser beams are used. The method of distributing the light on the optical axis is effective.

0003

[Problems to be Solved by the Invention] However, in the above conventional example, since one laser beam is divided into multiple optical axes, the output value of the laser beam is (
intensity) will also be divided. For example, when one laser beam is divided equally into four beams, the intensity of each beam is 1/4 of the original beam. Therefore, in laser processing, where the larger the amount of energy per unit time is, the faster the processing speed is, and the quality of the processed hole is also improved, conventional methods have a slower processing speed for one hole. It has been pointed out that this method does not lead to improved machining efficiency as much as expected. Also,
At the same time, it has been pointed out that the decrease in beam intensity leads to a decrease in hole quality.

[0004] Therefore, the present invention has been made in view of the above-mentioned problems, and its purpose is to reliably improve the efficiency of hole machining and to prevent deterioration in hole quality. The object of the present invention is to provide a laser hole machining method unlike any other.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems and achieve the objects, the laser hole machining method of the present invention uses a pulsed laser beam to By sequentially switching and irradiating a plurality of machining optical axes in synchronization when the laser beam is not excited, a laser beam that sequentially performs perforation of a plurality of workpieces installed on each of the plurality of machining optical axes. This method is characterized in that the laser beam is sequentially switched to another processing optical axis each time drilling of one hole in one workpiece is completed.

Further, in the laser hole processing method according to the present invention, a plurality of total reflection mirrors are provided on the irradiation optical axis of the laser beam, corresponding to the plurality of workpieces. It is characterized in that the laser beam is switched to the plurality of processing optical axes by moving each one independently.

Further, in the laser hole machining method according to the present invention, a laser beam is directed to the plurality of optical axes by a photo sensor disposed corresponding to each of the plurality of machining optical axes. It is characterized by detecting whether or not the

[0008]

[Operation] As described above, since the laser hole processing method according to the present invention is configured, the laser beam can be distributed sequentially onto several processing optical axes to perform drilling. Therefore, there is no need to move the position of the printed circuit board each time one hole is drilled, and several printed circuit boards can be processed with one positioning, improving processing efficiency.

In addition, since one laser beam is not divided, it is possible to prevent a decrease in the strength of the beam involved in the drilling process, and it is possible to shorten the processing time. High-quality drilling becomes possible.

[0010] Furthermore, the movement of the total reflection mirror is
By synchronizing with the non-excitation time of one pulse of the laser beam, it is possible to effectively use the non-excitation time of the laser, which is necessary for good drilling, and also to reduce the
There is no need to provide additional time for movement, further improving machining efficiency.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an outline of a laser hole machining apparatus to which an embodiment of the laser hole machining method is applied. In FIG. 1, reference numeral 1 denotes a laser oscillator that oscillates a laser beam, and a laser pulse oscillation control device 2 is connected to this laser oscillator 1 for controlling the oscillation state of the laser beam. On the irradiation optical axis of the laser oscillator 1, four total reflection mirrors 8A to 8D are connected in series, each totally reflecting the irradiated laser beam in a direction perpendicular to the irradiation optical axis. It is placed in the same condition. Of these four total reflection mirrors 8A to 8D, 8D is fixed, but the
The three total reflection mirrors 8A to 8C closer to the oscillator 1 are provided with mirror drive mechanisms 7A to 7C for retracting the total reflection mirrors 8A to 8C independently from the irradiation optical axis. It's coming. The mirror drive mechanisms 7A to 7C include a Z-axis drive that selectively retracts the total reflection mirrors 8A to 8C and controls the operation of sequentially distributing the laser beam from the laser oscillator 1 to each processing optical axis 17A to 17D. A driver controller 6 is connected.

Further, photosensors 10A to 10D are arranged at positions corresponding to the processing optical axes 17A to 17D of the laser beams totally reflected by the mirrors 8A to 8D, respectively. , from the detection signals of each photosensor 10A to 10D, each processing optical axis 17A
~17D is connected to a photodetector 9 which determines whether or not a laser beam is coming.

Furthermore, on each processing optical axis 17A to 17D,
Processing heads 11A to 11D each having a condensing lens therein for condensing a collimated laser beam to a single point are arranged. Then, this processing head 11A-1
1D are each held by a head drive device (not shown), and this head drive device drives the processing head 11A.
~11D are each independently moved in the optical axis direction, thereby changing the position of the laser beam focal point (each processing head 11A~
The focal position of the condensing lens in 11D moves in the optical axis direction, and the printed circuit boards 15A to 15D, which are workpieces to be described later, are moved in the optical axis direction.
Focused on top. This focusing operation is controlled by an autofocus control device 4 connected to the lens driving device.

Further, in front of the condenser lenses 11A to 11D on the optical axes, there are processing optical axes 17A to 17, as described above.
Corresponding to D, printed circuit boards 15A to 1 which are workpieces
5D is placed in a removable state on an X-Y table 12 that is movable left and right (X direction) and front and rear directions (Y direction) with respect to the plane of the paper. An NC control device 5 is connected to the X-Y table 12, and according to commands from the NC control device 5, the X-Y table 12 is driven, and the printed circuit boards 15A to 15D are connected to each processing optical axis. 17
Each time one hole is completed for A to 17D,
By moving in the X direction and the Y direction, a plurality of holes are formed on the printed circuit boards 15A to 15D.

The laser pulse oscillation control device 2, autofocus control device 4, NC control device 5, Z-axis drive driver controller 6, and photodetector 9 generate pulse signals for controlling the entire laser hole machining device. It is connected to the central control device 3.

Next, the operation of this laser hole machining apparatus will be explained. Here, a case is shown in which the laser beam is sequentially distributed onto four optical axes.

First, the printed circuit board 15A which is the workpiece
~15D is fixed on the XY table 12,
The X-Y table 12 is controlled by the command from the NC control device 5.
The printed circuit boards 15A to 15D are positioned relative to the respective processing optical axes 17A to 17D in order to drill the first holes, respectively. When the positioning is completed, a positioning completion signal is sent to the pulse signal centralized control device 3, which in turn sends a start signal to the autofocus control device 4.

The autofocus control device 4 controls a head drive device (not shown) to move the processing heads 11A to 11D, which are equipped with condensing lenses inside, in the optical axis direction, so that the laser beam is focused on the substrate. To focus on 15A to 15D,
Adjust the position of the condenser lens. When this focus position adjustment is completed, the autofocus control device 4 issues a focus position adjustment completion signal and sends it to the pulse signal centralized control device 3.

Next, the laser is applied to the printed circuit boards 15A to 15.
The processing point on D is irradiated, and at this time, the beam emitted from the laser oscillator 1 is directed to the mirror drive mechanism 7A.
It is selectively reflected by total reflection mirrors 8A to 8C in ~7C and fixed total reflection mirror 8D, and is sequentially irradiated onto printed circuit boards 15A to 15D. And mirror
Total reflection mirrors 8A to 8C are driven by drive mechanisms 7A to 7C,
For example, as shown by the broken line in the figure, by moving the laser oscillator 1 selectively away from the optical axis,
One of the four printed circuit boards 15A to 15D can be selected and irradiated with laser.

[0021] Here, the characteristics of laser drilling processing are as follows:
When drilling one hole, rather than continuously irradiating the beam, the beam is irradiated intermittently, and during the interval time set after the intermittent irradiation time, the heat dissipation of the drilled part of the printed circuit board is performed. It is known that better hole machining can be achieved by releasing a reactive gas.

Therefore, in order to selectively irradiate the printed circuit boards 15A to 15D with the laser beam as described above, the oscillation pulse of the laser and the driving timing of the total reflection mirrors 8A to 8D must be adjusted. Must be accurately synchronized. Therefore, strictly synchronized pulse signals are sent from the pulse signal centralized control device 3 to the laser pulse oscillation control device 2.
The signal is sent to the Z-axis drive driver/controller 6 which controls the mirror drive mechanisms 7A to 7D. According to this pulse signal, the laser oscillator 1 and the mirror drive mechanisms 7A to 7
By controlling D, the timing of the laser beam pulse and the timing of moving the total reflection mirrors 8A to 8D are synchronized, and the beam is directed to each of the processing optical axes 17A to 1.
It becomes possible to sequentially allocate to 7D.

By moving the total reflection mirrors 8A to 8D during the interval between the laser beam irradiation time and the next laser beam irradiation time, the total reflection mirrors 8A to 8D are moved during the interval time between the laser beam irradiation times and the next laser beam irradiation time. The interval time can be used effectively, and there is no need to provide a separate time for moving the mirror.

The photodetector 9 also includes a photosensor 10A.
10D, detects that light is coming to each optical axis 17A to 17D, and feeds back this light detection signal to the pulse signal central control device 3. Based on this optical detection signal, the pulse signal centralized control device 3 determines whether the timing of laser oscillation and the timing of driving the total reflection mirrors 8A to 8D are well synchronized. If an abnormality is detected, such as out of synchronization or light not reaching the required position, a command to stop the device is sent to each part of the device.

The laser beam is applied to each printed circuit board 15A to 1.
5D, each printed circuit board 15A to 1
When sufficient laser pulses have been irradiated to 5D for the drilling operation of the first hole, the pulse signal central control device 3
Sends a signal to the C control device 5 to indicate completion of drilling. NC control device 5
drives the X-Y table 12 and connects the printed circuit board 15.
A to 15D are positioned at the drilling position of the second hole. After that, in the same way as the first hole drilling operation, each printed circuit board 15
A to 15D are sequentially irradiated with the laser beam, and the drilling operation of the second hole is completed. In this way, the X-Y table 12
By repeating the movement and positioning of the board and the drilling operation by laser irradiation, all the holes in each printed circuit board 15A to 15D are bored.

Next, FIGS. 2 and 3 show the above-mentioned laser beam.
Regarding the distribution of the beams to each processing optical axis 17A to 17D,
This is a more specific explanation. In FIG.
All total reflection mirrors 8A are connected to the output optical axis of the oscillator 1.
-8D is on the optical axis, it moves to the first axis 17A, when the total reflection mirror 8A retreats from the optical axis, it moves to the second axis 17B, and when both the total reflection mirrors 8A and 8B retreat, it moves to the third axis 17C. This shows that when the total reflection mirrors 8A to 8C are retracted, the optical path of the beam is switched to the fourth axis 17D. FIG. 3 shows the laser oscillation situation in each state, that is, the laser beam pulse irradiated to each processing point.

In this case, although FIG. 3 shows a constant period and height (intensity) as the output waveform from the laser oscillator 1, as shown in FIGS. It is fully possible to perform operations such as changing the shape of the workpiece or the shape of the hole to be machined by changing the width, period, etc. In other words, the thermal conductivity and heat dissipation coefficient will change depending on the material, shape, hole shape, etc. of the workpiece. For workpieces with a small heat dissipation coefficient, increase the time for heat dissipation by increasing the interval between irradiation times and the next irradiation time. It is possible to perform the following operations. In addition, especially as shown in Figure 4, 1
It is also possible to change the height, width, and period of the pulse for each pulse during the process of machining one hole, and by changing the pulses in this way, machining can be performed that matches the optimal machining conditions for the hole. be able to.

As explained above, according to one embodiment, by moving the mirror at a timing synchronized with the timing of laser oscillation, the laser beam is sequentially placed on a plurality of optical axes. It is possible to distribute the holes and perform drilling. Therefore, there is no need to move the position of the printed circuit board each time one hole is drilled, and several printed circuit boards can be processed with one positioning, improving processing efficiency.

Furthermore, since one laser beam is not divided, it is possible to prevent a decrease in the strength of the beam involved in the drilling process, and it is possible to shorten the processing time. High-quality drilling becomes possible.

The present invention can be applied to modifications or variations of the above embodiments without departing from the spirit thereof.

For example, in one embodiment, laser beam
Although the case where the system is distributed to four axes has been described, it goes without saying that the number of axes may be increased or decreased.

[0032]

Effects of the Invention As explained above, in the laser hole processing method of the present invention, the laser beam can be distributed sequentially onto a plurality of processing optical axes to perform the drilling process. There is no need to move the position of the printed circuit board every time one hole is drilled, and several printed circuit boards can be processed with one positioning, which has the effect of improving processing efficiency. .

Furthermore, since one laser beam is not divided, it is possible to prevent a decrease in the strength of the beam involved in the drilling process, and it is possible to shorten the processing time. This has the effect of enabling high-quality drilling.

Furthermore, the movement of the total reflection mirror is controlled by laser beams.
By synchronizing with the non-excitation time of one pulse of the laser beam, it is possible to effectively use the non-excitation time of the laser, which is necessary for good drilling, and also to reduce the
There is no need to provide additional time for movement, which has the effect of further improving machining efficiency.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a laser hole machining apparatus to which a laser hole machining method according to an embodiment is applied.

FIG. 2 is a diagram showing the state of each mirror when a laser beam is distributed to each optical axis.

FIG. 3 is a diagram showing output states of laser pulses corresponding to the states of each mirror in FIG. 2;

[Figure 4],

5 is a diagram showing an application example of the laser pulse output state of FIG. 3; FIG.

[Explanation of symbols]

7A~7C Mirror drive mechanism 8A~8D
Total reflection mirror 9 Photodetector 10A~10
D Photosensors 11A to 11D Processing head (including condensing lens) 12
X-Y table 15A~15
D Printed circuit board 17A to 17D Processing optical axis

Claims (3)

[Claims] Claim 1: By sequentially switching and irradiating a plurality of processing optical axes with a laser beam oscillated in a pulsed manner in synchronization with the non-excitation of the laser beam, the plurality of processing beams are This is a laser hole processing method in which holes are sequentially drilled into a plurality of workpieces installed on a shaft, and each time the drilling of one hole in one workpiece is completed, the laser - A laser hole machining method characterized by sequentially switching the laser beam to other machining optical axes. 2. A plurality of total reflection mirrors provided on the irradiation optical axis of the laser beam, corresponding to the plurality of workpieces.
2. The laser hole machining method according to claim 1, wherein said laser beam is switched to said plurality of machining optical axes by independently moving said laser beams. 3. A photo sensor disposed corresponding to each of the plurality of processing optical axes detects whether or not a laser beam is directed to the plurality of optical axes. The laser hole processing method according to claim 1.