JP3194248B2 - Laser drilling apparatus and laser drilling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser drill, and more particularly, to a laser drill capable of high-speed machining.

[0002]

_2. Description of the Related Art Conventionally, there has been known a laser drill device for making a hole in a workpiece such as a printed circuit board by using a laser beam from a YAG laser, a CO ₂ laser, an excimer laser, or the like.

In this type of laser drill, a workpiece is held on a work stage, the position of the workpiece is determined, and then a laser beam is irradiated to perform drilling. Here, in the conventional laser drilling apparatus, in order to improve the processing speed, a laser beam can be scanned on the surface of the workpiece using a galvano scanner, or a plurality of holes can be simultaneously formed using a multi-hole mask. Or to form.

As described above, the conventional laser drill device is
In order to increase the processing speed, a galvano scanner, a multi-hole mask, etc. are used, but in any case, after the movement of the workpiece by the work stage is completed, the laser Processing is performed.

Here, the pulse oscillation of the laser is 1 kHz.
Since high-frequency oscillations such as z and 2 kHz are possible, for example, when performing one-shot processing one hole at a time,
Processing at 1000 holes / second and 2000 holes / second is theoretically possible. Furthermore, when performing two-hole simultaneous processing, 2000
Holes / sec and 4000 holes / sec are theoretically possible.

[0006] However, for a single movement and stop of the work stage, even if the work stage can be moved at a high speed, the work stage can be moved in a range of 0.2-0.
It takes 3 seconds. In other words, in reality, depending on the time required to move and stop the workpiece by the work stage,
It can be said that the processing speed of the laser drill device is determined.

[0007] Even when the work stage is not moved at all, the processing speed is limited to about 500 holes / second because the response frequency of the galvano scanner is about 500 Hz in the conventional laser drilling apparatus. .

As described above, the conventional laser drilling apparatus has a problem that it takes time to move and stop the work stage and the response of the galvano scanner, and the processing speed is limited.

Therefore, the inventor has proposed a laser drilling apparatus capable of continuously drilling by oscillating a laser periodically while moving a workpiece at a constant speed.

[0010]

However, in a laser drilling apparatus that irradiates a laser beam while moving a workpiece, the shape of the formed hole is different from the shape of the hole of the mask, and the shape of the hole extends in the moving direction. There is a problem that it becomes. That is, the conventional mask has a circular mask hole, and there is a problem that the hole formed in the workpiece becomes an oval.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser drilling device that irradiates a laser beam while moving a workpiece, and can form a hole having a desired shape.

[0012]

According to the present invention, there is provided a laser oscillator for emitting laser light, a mask having a plurality of mask holes formed therein, and an optical system for irradiating the plurality of mask holes with the laser light. A work stage for holding and moving the workpiece, and control means for controlling both oscillation of the laser oscillator and movement of the workpiece by the work stage, and controlling the work stage to control the work stage. In a laser drilling apparatus for performing laser drilling by oscillating the laser oscillator according to the position of the work stage while moving a workpiece, the shape of the mask hole is shortened in a moving direction of the workpiece, and It is long and substantially rectangular in the direction perpendicular to the direction of movement.
Set the moving speed of the workpiece to the short length of the hole formed in the workpiece.
A laser drilling device characterized in that the ratio of the side to the long side is determined to be 75% or more .

Further, according to the present invention, the workpiece is periodically irradiated with laser light from a laser oscillator through a mask hole while moving the workpiece, so that a hole is continuously formed in the workpiece. In the laser drilling method characterized by drilling a hole, the mask hole is a substantially rectangular mask hole that is short in a moving direction of the workpiece and long in a direction orthogonal to the moving direction, The shape of the hole formed at the speed at which the ratio of the short side to the long side becomes 75% or more.
While moving the workpiece, the laser light is applied to the workpiece.
And a laser drilling method characterized by irradiating the laser beam.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a laser drill device according to an embodiment of the present invention. This laser drill device is divided by a laser oscillator 11 that emits laser light, a splitter 12 that splits the laser light from the laser oscillator 11 into two, a mirror 13 that reflects one of the laser lights split by the splitter 12, and a splitter 12. A collimator lens 14 into which the other laser beam enters, a kaleidoscope 15 for making the energy distribution of the laser beam passing through the collimator lens 14 uniform, a bundle fiber 16 in which a plurality of small diameter optical fibers are bundled, a large diameter optical fiber 17, a bundle fiber A mask 18, a shielding plate 19 for blocking a laser beam passing through a hole in the mask, an imaging lens 20 for condensing the laser beam passing through the mask, and a workpiece are mounted on the tip of the optical fiber 16 and the large-diameter optical fiber 17. Work stage (linear stage) 21 for performing And a control unit 22 for controlling the laser oscillator to control the Kusuteji.

As the laser oscillator 11, a pulsed laser, for example, a YAG laser can be used.

The splitter 12 splits the laser beam from the laser oscillator 11 into a laser beam used for ordinary drilling and a laser beam for forming an alignment hole.

The mirror 13 guides the laser light for forming an alignment hole branched by the splitter 12 to a large-diameter optical fiber 17.

The collimator lens 14 includes the splitter 1
The laser light for normal drilling that has passed through 2 is focused.

The kaleidoscope 15 converts a Gaussian beam, which is a laser beam from the collimator lens 14, into a beam having a uniform intensity distribution.

The bundle fiber 16 is a bundle of a plurality of small diameter optical fibers, and
Is converted into a plurality of small-diameter laser lights, and the mask 18 is irradiated with the emitted light. Here, the small diameter means that the diameter is smaller than the large diameter optical fiber 17 for guiding the laser light for forming the alignment hole and the emitted light. The light emitted from these small-diameter optical fibers can be regarded as having uniform intensity by the action of the kaleidoscope 15.

The large diameter optical fiber 17 guides the laser light reflected by the mirror 13 to the mask 18. As shown by the arrow A, the large-diameter optical fiber 17 can be removed from the optical path of the laser light reflected by the mirror 13.

The mask 18 has a plurality of mask holes of a predetermined shape formed at predetermined intervals. The shape of the mask will be described later. In addition, the interval and the diameter of the mask hole in the conventional mask are set to about 10 times the interval and the diameter of the hole formed in the workpiece, respectively. The exit ends of the small-diameter optical fiber and the large-diameter optical fiber of the bundle fiber 16 are disposed so as to face the mask holes formed in the mask 18. In addition,
The size of the mask hole must be smaller than the diameter of the laser light emitted from these optical fibers.

The shielding plate 19 is used to block a laser beam passing through the mask hole of the mask 18 and is used for forming only an alignment hole or adjusting the number of holes to be formed. used.

The imaging lens 20 reduces the mask image at a predetermined magnification and forms an image on the surface of the workpiece placed on the linear stage 21. As this imaging lens, a bi-telecentric lens that is resistant to vertical displacement in the figure is used. By using such a lens, the laser beam that has passed through the mask hole can be made to enter the workpiece almost perpendicularly.

The linear stage 21 has a holding portion for holding and fixing the workpiece. The holding unit includes, for example, a ridge that contacts two adjacent sides of the workpiece, and a magnet that suppresses the other two sides. The linear stage 21 can move the held workpiece in the x direction and the y direction. And at least in one direction,
The workpiece can be moved at a constant speed.

The control unit 22 controls the drive of the linear stage 21 and controls the oscillation of the laser oscillator 11.

Hereinafter, the operation of the laser processing apparatus will be described.

First, a workpiece 22 such as a ceramic green sheet is placed on a linear stage 21, and the workpiece 22 is held and fixed to the linear stage 21.

Next, the controller 22 controls the linear stage 21
Is moved at a constant speed in the y direction in the figure. At the same time, the laser oscillator 11 periodically oscillates according to the position of the linear stage. That is, the control unit 22 causes the laser oscillator 11 to oscillate every time the linear stage moves a predetermined moving distance while moving the linear stage at a constant speed in the y direction.

At this time, when forming the alignment hole, the large-diameter optical fiber 17 is arranged on the optical path of the laser beam reflected by the mirror 13. Conversely, when no alignment hole is formed, the large-diameter optical fiber 17 is removed from the optical path of the laser light reflected by the mirror 13.

Further, according to the number of holes to be formed,
The shielding plate 19 is arranged so as to block the laser beam from the mask.

The laser light emitted from the laser oscillator 11 is split by the splitter 12, and one is reflected by the mirror 13. The other laser beam split by the splitter 12 is condensed by the collimator lens 14 and enters the kaleidoscope while diffusing. The kaleidoscope converts the laser beam, which is a Gaussian beam, into a laser beam having a uniform light intensity and causes the laser beam to enter each small-diameter optical fiber of the bundle fiber 16. Bundle fiber 1
The laser beam incident on 6 is irradiated toward the mask hole of the mask 18.

On the other hand, the laser beam reflected by the mirror 13 enters the large diameter optical fiber 17 when the large diameter optical fiber 17 is placed on the optical path. The laser beam incident on the large-diameter optical fiber is applied to a mask hole for an alignment hole on the mask 18.

A part of the laser beam applied to the mask 18 passes through the mask hole, is condensed by the imaging lens, and is applied to the workpiece.

In the workpiece irradiated with the laser beam, laser ablation occurs, and a hole is instantaneously formed.

Here, the shape of the mask is a rectangle or an oval that is long in the x direction and short in the y direction, as shown in FIG. 2A or 2B. In the present embodiment, since the workpiece is moving at a constant speed in the y direction, the shape of the hole formed in the workpiece is as shown in FIG. Since the shape to be formed is determined by the pulse width of the laser beam and the moving speed of the workpiece, the control unit 22 controls the linear stage so that the ratio of the long side to the short side of the processing hole becomes 75% or more. the moving speed of is adjusted.

As described above, in the present embodiment, the above operation can be repeated according to the position of the linear stage 21 while moving the linear stage 21 to continuously form holes at predetermined intervals in the workpiece. The shape of the hole can be a predetermined shape (substantially square).

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a laser oscillator 11, a YAG laser is used. Its characteristics are: output: 400 W, energy: 1.5
J / pulse, pulse oscillation frequency: about 250 Hz, emission light: Gaussian beam.

As the bundle fiber 16, a bundle of 16 small-diameter optical fibers having an emission light diameter of 1.2 mm is used.

The mask 18 has a long side of 0.25 to 1.0
The mask holes of an arbitrary size are arranged in a straight line at an interval of 8 mm with 16 holes having a range of mm and a short side of about 1/3 thereof. It is assumed that the size of the alignment mask hole is larger than this.

The imaging lens 20 has 16 holes formed in the mask, the distance between the holes is 8 mm, and 16 ×
Since 8 = 128, a lens having a larger diameter, for example, a diameter of 150 mm is used. In addition, the imaging lens 2
0 means that the mask image is reduced to 1/10 and projected onto the workpiece.

The linear stage 21 has a scale with a resolution of 0.1 μm and runs at a maximum speed of 100 mm / sec.

In the above configuration, 135 mm (x
A case of processing an area of (direction) × 135 mm (y direction) will be described.

When holes are formed at intervals of 0.8 mm in the x direction and 0.4 mm in the y direction, 135 mm は
Since (0.8 mm × 16) ≒ 10.5, 11 scans are required. For the y direction, 13
Since 5 mm ÷ 0.4 mm = 337.5, 338 scans are required. In the present embodiment, scanning in the y direction is performed at a constant speed.

In the y direction, two holes having a pitch of 0.4 mm
If it is assumed to be formed at a frequency of 50 Hz, 0.4 mm ×
A moving speed of 250 = 100 mm / sec is required. In other words, when the linear stage 21 is moved at a speed of 100 mm / sec and processed by laser light from a laser oscillator having a pulse oscillation frequency of 250 Hz, holes having a pitch of 0.4 mm can be formed. At this time, the time required for one scan in the y direction is 135 mm ÷ 100 mm / sec = 1.3.
5 seconds.

In the x direction, it is assumed that a movement of 12.8 mm is required, and the time required for the movement is 1 second.

From the above, in order to process an area of 135 mm × 135 mm using the laser drilling apparatus according to the present embodiment, 1.35 seconds × 11 scans + 1 second × 11 times ≒ 26 seconds. Takes time. The number of holes formed at this time is 135 ÷ 0.8 = 16 in the x direction.
8.75, so 169 holes. 135 ° in y direction
Since 0.4 = 337.5, there are 338 holes. Therefore, the number of holes formed in this area is 169 × 338
= 57122 holes. Therefore, the average processing speed of this laser drill device is 57122 ÷ 26 = 2197 holes /
Seconds.

The shape of the hole formed in the workpiece according to the present embodiment was substantially square, with the ratio of the long side to the short side being 75% or more.

[0050]

According to the present invention, a mask hole of a laser drill device for irradiating a laser beam from a laser oscillator while moving a workpiece is shortened in the moving direction of the workpiece.
By making the rectangle long in the direction perpendicular to the moving direction, the shape of the hole formed in the workpiece can be made closer to a square.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is a view for explaining the shape of a mask hole of the mask of FIG. 1;

FIG. 3 is a diagram for explaining a shape of a hole formed in a workpiece;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Laser oscillator 12 Splitter 13 Mirror 14 Collimator lens 15 Calliscope 16 Bundle fiber 17 Large diameter optical fiber 18 Mask 19 Shielding plate 20 Imaging lens 21 Work stage (linear stage) 22 Control part 23 Workpiece

Claims (2)

(57) [Claims] 1. A laser oscillator for emitting a laser beam, a mask having a plurality of mask holes formed therein, an optical system for irradiating the plurality of mask holes with the laser beam, and an object for holding and moving a workpiece. Work stage, oscillation of the laser oscillator, and a control means for controlling both the movement of the workpiece by the work stage, while controlling the work stage to move the workpiece in a predetermined direction , In a laser drilling apparatus that performs laser drilling by oscillating the laser oscillator in accordance with the position of the work stage, the shape of the mask hole is reduced in a moving direction of the workpiece, and in a direction orthogonal to the moving direction. long,
While making it approximately rectangular , the moving speed of the workpiece is
The ratio of the short side to the long side of the hole formed in the workpiece is 75
% . 2. A method of continuously irradiating a laser beam from a laser oscillator through a mask hole to the workpiece while moving the workpiece in a predetermined direction, thereby continuously drilling the workpiece. In the laser drilling method, the mask hole is formed in the workpiece using a substantially rectangular mask hole that is short in the moving direction of the workpiece and long in a direction perpendicular to the moving direction. The shape of the hole to be processed is such that the ratio of the short side to the long side is 75% or more .
Irradiating the workpiece with the laser beam while moving
Laser drilling method is characterized in that the so that.