JP2000084691A - Laser beam machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam machining device that enhances energy density in the machining point of a laser beam used for machining, that reduces the size and the output of a laser oscillator, that decreases gas exchanging frequency inside the laser oscillator, and that lowers running cost as well as extending the life of the device. SOLUTION: In a laser beam machining device 20 that converges a laser beam from a laser oscillator 1 in nearly a long narrow shape on a mask 11 having a pattern corresponding to a machining shape for a workpiece, through a beam shaping part 6, beam expander 7, homogenizer 8 and a condenser lens 9; a cylindrical lens 10 is arranged between the condenser lens 9 and the mask 11, limiting the irradiation angle of the laser beam emitted to the mask 11 only in the narrow width direction of a narrow converging shape formed on the mask 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus for performing laser processing efficiently and economically by increasing the density of light energy of a laser beam output from a laser oscillator. For example, the present invention relates to a laser processing apparatus for processing an ink jet nozzle hole of an ink jet printer.

[0002]

2. Description of the Related Art Conventionally, as a laser processing apparatus for processing the above-described ink jet nozzle hole, as shown in FIG. 4, a laser beam oscillator 1, a beam shaping section 5 for shaping a laser beam A, and A mask 11 having a laser processing shape on the workpiece B, that is, a hole pattern (not shown) in which a plurality of nozzle holes are arranged in a row, and condensing optical means 9 for condensing and irradiating the mask 11 with a laser beam A And the mask 11
Projection optical means (imaging optical means) 12 for forming an image of the hole pattern on the workpiece B at a predetermined magnification (usually a reduction magnification)
The one having the following is common.

The laser processing device 50 shown in FIG.
A beam expander 7 for expanding the laser beam A and a pair of fly-eye lenses 8.8 as a beam flattening optical system (homogenizer) are used. After uniformizing the beam intensity and controlling the light output by dispersing the beam into a vertically long beam, the narrow and rectangular laser beam A condensed by a condenser lens 9 as a condensing optical system is placed on a predetermined position of a mask 11. (Hole pattern position). The laser beam A thus transmitted through the mask 11
Are imaged on the workpiece at a predetermined magnification (for example, 1/4 or 1/5) by the imaging lens 12 as the projection optical means, and correspond to the hole patterns arranged in a row of the mask 11. A plurality of nozzle holes (not shown) are formed on the workpiece B,
A plurality of nozzle holes (for example, 64) are formed in a row.
Here, while the workpiece B on the XY table 5 is moved by a predetermined dimension in the X direction or the Y direction, the laser beam A is again output and radiated by the laser beam oscillator 1 to emit a predetermined number of nozzle holes. Are drilled at a constant pitch.
Reference numerals 2, 3, and 4 in the figure are total reflection mirrors.

[0004]

However, the above-mentioned conventional laser processing apparatus has room for improvement in the following points. That is, the laser beam is uniformly irradiated on the mask, but the shape is rectangular as shown in FIG. 3A, and the loss of the laser beam A when homogenizing by the homogenizer 8 is very large. Therefore, the energy density at the processing point on the workpiece B was low. For this reason, the output of the laser oscillator 1 must be increased,
The cost of the device is high and the running cost is high. In addition, there is a problem that the built-in gas deteriorates quickly because the laser oscillator 1 is used in a state where the output is high, and the life of the laser oscillator 1 is very short because the laser oscillator 1 is used at a high voltage. Further, in the homogenizer 8, there is a method of subdividing elements constituting a fly-eye lens for dispersing the laser beam A into a plurality of vertically long beams, but the homogenizer 8 becomes very expensive.

Meanwhile, in a general laser processing apparatus, as shown in FIG. 5, a numerical aperture NA (refraction angle) which is a condensing angle in the Y direction which is condensed by a condenser lens 9 and irradiated on a mask 11 is shown. In general, the numerical aperture NA in the X direction is equal to the product of the ratio N and the sine (sin θ) of the condensing angle (also referred to as the irradiation angle) θ. Condensed by the mask 11
The numerical aperture NA in the Y direction irradiated on the mask 11 is different from the numerical aperture NA in the X direction irradiated on the mask 11, that is, the focusing angle of the laser beam A in the X direction as shown in FIG. By increasing θ and increasing the numerical aperture NA, the light-collecting characteristic was changed from the conventional one and processing of the nozzle hole was performed on the workpiece B. The nozzle hole was free from distortion in processing. The finish was fine, and the processing time for the workpiece B was also reduced. This is because the energy density of the laser beam A was increased by narrowing the irradiation state of the laser beam A only in the X direction and enlarging the converging angle θ to increase the numerical aperture NA. In this case, it was confirmed that it was not necessary to use the magnetic head in a state where the numerical apertures NA in the X direction and the Y direction were matched.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is possible to improve the energy density of a laser beam used for laser processing at a processing point, to reduce the size of a laser oscillator, and to reduce the output of a laser oscillator. It is an object of the present invention to provide a laser processing apparatus that can reduce the frequency of gas exchange in the inside, reduce running costs, and extend the life of the apparatus.

[0007]

According to a first aspect of the present invention, there is provided a laser processing apparatus comprising: a laser beam oscillator; and a beam shaping unit for shaping a laser beam emitted from the oscillator. A beam expander for expanding the laser beam output from the shaping unit, a homogenizer for homogenizing the laser beam output from the beam expander, and a laser beam output from the homogenizer to the workpiece. In a laser processing apparatus having a condenser lens that condenses light into a substantially elongated shape on a mask having a pattern corresponding to the processing shape of the above, irradiation of a laser beam directed toward the mask between the condenser lens and the mask The angle,
Lens means for narrowing the light condensing shape formed on the same mask in a narrow width direction is arranged.

According to the laser processing apparatus of the first aspect having the above configuration, the irradiation light shape (substantially elongated shape) of the laser beam applied to the mask has a narrow width direction (a width direction side narrower than the longitudinal direction). The energy density of the laser beam is improved by narrowing down only in (2). Therefore, for example, the laser oscillator can be made smaller than the conventional laser processing apparatus, and when a laser oscillator having the same size as the conventional one is used, the output (power) can be reduced. The deterioration of the gas to be sealed is delayed, the gas can be used for a long time, and the life of the laser oscillator is extended. This means that when using a laser processing apparatus that is extremely expensive and has a high running cost, the running cost as well as the initial cost of the laser processing apparatus is reduced, and the processing cost can be significantly reduced.

[0009] As described in claim 2, a cylindrical lens can be used as the lens means.

[0010] According to the laser processing apparatus of the second aspect,
By using the cylindrical lens, it is possible to keep the substantially elongated shape of the laser beam irradiated on the mask constant in the longitudinal direction and hardly change it, and to narrow down the laser beam only in the width direction.

A laser beam oscillator, a beam shaping unit for shaping a laser beam emitted from the oscillator, and a beam expander for expanding the laser beam output from the shaping unit And a homogenizer for homogenizing the laser beam output from the beam expander, and condensing the laser beam output from the homogenizer in a substantially elongated shape on a mask having a pattern corresponding to a processing shape on a workpiece. In a laser processing apparatus having a condenser lens, a numerical aperture (NA) of a laser beam converged from the condenser lens toward the mask has a smaller width than a longitudinal direction of the condensed shape formed on the mask. In the direction of.

According to the laser processing apparatus of the third aspect having the above configuration, the numerical aperture (NA) of the laser beam applied to the mask, that is, the product of the refractive index N and the sine of the converging angle θ (sin θ). However, by increasing the condensed light shape (almost elongated shape) at the irradiation position on the mask in the width direction narrower than the longitudinal direction, the width of the condensed light shape on the mask is narrowed and the energy density of the laser beam is improved. (See FIG. 3B). Therefore, the conventional numerical aperture (NA)
For example, as compared with a general laser processing apparatus (see FIGS. 4 and 5) in which the laser oscillator is commonly used in the X direction and the Y direction, the laser oscillator can be made smaller. In addition, the output (power) can be reduced, and as a result, the deterioration of the gas sealed in the laser oscillator is slowed down, the laser can be used for a long time, and the life of the laser oscillator is extended. On the other hand, there is a difference in the numerical aperture (NA) between the Y direction and the X direction, but there is no processing problem such as distortion on the workpiece, as described above, since it has been demonstrated in the processing of the nozzle hole. I can say.

According to a fourth aspect of the present invention, lens means can be arranged between the condenser lens and the mask.

According to the laser processing apparatus of the fourth aspect,
After homogenizing the beam intensity and controlling the light output by, for example, dispersing the laser beam into a number of longitudinal beams in the homogenizer, a number of the longitudinal beam portions are condensed by a condenser lens to be elongated. A rectangular laser beam is applied to a predetermined position (hole pattern position) of the mask, but the laser beam condensed by the condenser lens is further compared with the longitudinal direction by a lens means disposed between the mask and the condenser lens. By narrowing down the numerical aperture (NA) in the narrow width direction, the condensing shape at the irradiation position on the mask is further condensed (contracted) in the narrow width direction.

[0015] The homogenizer may be a fly-eye lens for dispersing the laser beam into a plurality of elongated beams, and the condenser lens may focus the plurality of elongated beams. Preferably, it is

According to the laser processing apparatus of claim 5,
The laser beam output from the laser beam oscillator and usually shaped into a square by the beam shaping unit is expanded by the beam expander, and then dispersed by the homogenizer into a number of vertically long beams.
The beam intensity is made uniform and the light output is controlled.
Then, a number of vertically long beams are condensed by a condenser lens as a condensing optical system, and a narrow and rectangular laser beam is irradiated to a predetermined position of the mask. The laser beam transmitted through the mask in this way is usually imaged on a workpiece at a predetermined reduction magnification (for example, 1/4, 1/5) by an imaging lens as a projection optical system, and a hole is formed. Laser processing is performed according to the pattern, but unlike the conventional light-collecting characteristics, the numerical aperture NA is narrower than the longitudinal direction.
Laser beam is narrowed so that
As in the case of the laser processing apparatus of claim 1, the energy density is improved as compared with the conventional processing apparatus, and the processing can be finished finely. Therefore, the laser oscillator can be reduced in size, the output (power) can be reduced, and The deterioration of the gas to be sealed is delayed, the gas can be used for a long time, and the life of the laser oscillator is extended.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the laser processing apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is an overall schematic view showing an embodiment of a laser processing apparatus for processing an ink jet nozzle hole of an ink jet printer. FIG. 2 is a view showing a laser beam condensed by a condenser lens in the processing apparatus of FIG. FIG. 3A is an enlarged schematic plan view showing a state where the light is further narrowed in one direction (narrow width direction) by a cylindrical lens and is focused on a mask. FIG. 3A shows a laser beam shape on the mask before the cylindrical lens is inserted. FIG. 3 is an enlarged front view showing (light collecting shape).
(b) shows the shape of the laser beam on the mask after the cylindrical lens is inserted (light-condensing shape) in the apparatus shown in FIG.
It is a front view which expands and shows.

As shown in FIG. 1, in the laser processing apparatus 20 of this embodiment, an excimer laser beam (KrF laser beam) A having a wavelength of, for example, 248 nm output (emitted) from the laser oscillator 1 The light is refracted in the right-angle direction via total reflection mirrors 2, 3, and 4 arranged at an angle of 45 °, and reaches a processing table 5 that can selectively move the workpiece B in the X and Y directions. A beam shaping unit 6 for shaping the laser beam A is arranged between the laser oscillator 1 and the first mirror 2. In this example, the beam shaping unit 6 includes a concave lens and a convex lens, and shapes the laser beam A having a rectangular cross-sectional shape emitted from the laser oscillator 1 into a square shape.

The laser beam A is refracted at right angles by the first mirror 2 and travels straight upward in the drawing. First mirror 2 and third
A beam expander (Beam Expander) 7 for expanding the laser beam A is disposed between the mirror 3 and the mirror 3.
In this embodiment, the beam expander 7 includes a pair of convex lenses and the like. Downstream of the third mirror 3, a pair of fly-eye lenses (Fly-eye-
Lenz) 8.8 are arranged to face each other. The laser beam A, which is refracted by the third mirror 3 in the right angle direction and travels straight in the horizontal direction to the right side of the figure,
By dispersing the beam into a number of vertically elongated beams at 8, the beam intensity is made uniform and the light output is controlled.

On the downstream side of the fly-eye lens 8, a condenser lens 9 as a condensing optical means is arranged. The condenser lens 9 condenses a large number of vertically long beams to form a narrow and rectangular laser beam A. Then, the light is condensed at a predetermined position (hole pattern position) of the mask 11 disposed downstream of the condenser lens 9. The condensed shape to be condensed and irradiated on the mask 11 is a rectangle (rectangle) having a slightly wider width in the conventional general laser processing apparatus 50 (FIG. 4), as shown in FIG. However, in the present invention, as a characteristic configuration, a cylindrical lens (Cylindrical) is used.
Lenz) 10 is arranged between the condenser lens 9 and the mask 11.

As is well known, the cylindrical lens 10 has a function of hardly changing the laser beam passing therethrough in the major axis direction (longitudinal direction), and condensing (squeezing) it only in the minor axis direction (narrow width direction). Have. For this reason, the condensing shape condensed and irradiated on the mask 11 is a narrow rectangle (rectangle) as shown in FIG. That is, when the laser beam A passes through the cylindrical lens 10, it is focused only in the width direction (X direction) and is irradiated on the mask 11. As a result, the energy density of the laser beam A irradiated and focused on the mask 11 increases.

The mask 11 is provided with a hole pattern corresponding to a plurality of nozzle holes for ink ejection, and the mask 11 is held by a mask holder (not shown).
The laser beam A transmitted through the hole pattern of the mask 11 is
The light is refracted at right angles by the third mirror 4 and travels straight downward in the figure. On the downstream side of the third mirror 3, the processing table 5 on which the workpiece B is movable in the X and Y directions.
Is placed on top. The working table 5 can be moved up and down in the vertical direction.

Further, the third mirror 3 and the processing table 13
An image forming lens (also referred to as a projection lens) 12 is disposed between them. The image forming lens 12 forms an image of the laser beam A (image of the laser beam A) transmitted through the hole pattern of the mask 11 on the workpiece B by reducing it to a predetermined magnification (in this example, 1/5). Laser processing is performed corresponding to the 11 hole patterns. In this example, a polyimide sheet (about 100 μm in thickness), which is a polymer material, is used for the workpiece B, and a plurality of ultra-precision fine nozzle holes (about 30 μm in diameter) are formed in a row by the laser beam A. Is established. After a group of nozzle holes have been machined, the machining table 5 is driven to move the workpiece B in the X direction by a predetermined pitch, and the area to be machined on the workpiece B is located immediately below the imaging lens 12. And the focal point of the imaging lens 12 is
The processing table 5 is also moved in the vertical direction so as to focus on the top. Then, the laser beam A is output again by the laser oscillator 1, and a group of nozzle holes is further processed.

According to the laser processing apparatus 20 of the present embodiment having the above configuration, the laser beam A condensed and irradiated on the mask 11 is directed in a narrow width direction as shown in FIG. Since the energy density of the laser beam A has been improved by squeezing to completely cover the hole pattern 11a of the mask 11, a predetermined number of workpieces B are formed on the workpiece B by the laser beam A transmitted through the hole pattern of the mask 11. The nozzle hole was finely machined and the machining time was shortened. Further, as described above, the laser beam A applied to the mask 11 (or the workpiece B) is narrowed down in only one direction (XX direction) as shown in FIGS. The converging angle θ ′ is different from the converging angle θ in the other orthogonal direction (Y-Y direction). In other words, the numerical aperture NA in the X direction and the numerical aperture NA in the Y direction are different as a result.
Again, the slightly wider rectangular light-collecting region as shown in FIG. 3A is condensed in a narrower width direction than the longitudinal direction, and the narrower rectangular light-collecting region as shown in FIG. Although the laser beam A is condensed in the light-collecting region and the energy density is improved, in the present invention, the laser beam A is narrowed down so that the hole pattern of the mask 11 is completely covered by the laser beam A-light collecting region. Therefore, even if the numerical apertures NA in the X direction and the Y direction are different, it is considered that there is no problem in processing. In particular, as in the above embodiment, the cylindrical lens 1
It is epoch-making that the improvement of the energy density of the laser beam A can be achieved by adding a simple configuration in which 0 is disposed between the mask 11 and the condenser lens 9.

By employing the present invention, the laser oscillator 1 can be made smaller, and if the laser oscillator 1 is not made smaller, the output (power) can be reduced as compared with the conventional case. Deterioration of the laser oscillator 1 is delayed, the laser oscillator 1 can be used for a long time, and the life of the laser oscillator 1 is prolonged. In addition, laser oscillator 1
As a result, the output required for emitting the laser beam A can be provided with a margin, so that even if the laser oscillation output decreases during processing or during long-term use, it can be easily handled by increasing the output. Laser processing can be stably performed over a long period of time.

The embodiment of the laser processing apparatus of the present invention has been described above, but the present invention can be implemented as follows.

(1) The image forming lens 12 is omitted and the mask 1
The present invention can be similarly implemented in a contact mask method in which 1 is directly fixed on the workpiece B.

(2) The lens means to be inserted and arranged in front of the mask 11 is not limited to the cylindrical lens 10 as long as it can focus the laser beam only in one specific direction.

(3) In addition to the processing of the nozzle hole, for example, the workpiece B can be changed to ceramics, or a groove can be processed.

(4) The laser beam may be a gas other than KrF as long as the laser beam has a substantially rectangular cross section.

[0032]

As is apparent from the above description,
The laser processing apparatus according to the present invention has the following excellent effects.

(1) According to the first aspect of the present invention, the condensing shape (substantially elongated shape) of the laser beam applied to the mask is narrowed in a narrow width direction (width direction narrower than the longitudinal direction). Since the energy density of the laser beam is improved, for example, the laser oscillator can be made smaller than that of the conventional laser processing apparatus, and when a laser oscillator of the same size as the conventional one is used, the output (power) is reduced. In addition to the reduction, the gas sealed in the laser oscillator is slowed down, can be used stably for a long time, and the life of the laser oscillator is extended. As a result, the running cost as well as the initial cost of the processing device is reduced, and the processing cost is significantly reduced, which is economical.

(2) According to the second aspect of the present invention, the condensing shape of the laser beam irradiated on the mask is kept constant without changing in the longitudinal direction by simply adding a cylindrical lens. In addition, since the squeezing can be performed only in the width direction, the running cost can be significantly reduced without increasing the cost of the apparatus as compared with the conventional processing apparatus.

(3) According to the third aspect of the present invention, the numerical aperture (NA) of the laser beam applied to the mask, that is, the product of the refractive index N and the sine (sin θ) of the converging angle θ is calculated on the mask. Since the width is increased in the direction of the width narrower than the longitudinal direction of the light shape (substantially elongated shape), the direction of the narrow width of the converging shape on the mask is contracted, and the energy density of the laser beam is improved. Therefore, for example, in comparison with a conventional laser processing apparatus in which the numerical aperture (NA) is common in the X direction and the Y direction, for example, the laser oscillator can be made smaller, and when a laser oscillator having the same size as the conventional one is used. The same effect as the invention of claim 1 can reduce the output (power), delay the deterioration of the gas sealed in the laser oscillator, stably use the laser for a long time, and extend the life of the laser oscillator. Is exhibited.

(4) According to the fourth aspect of the present invention, with the addition of a simple structure in which a lens means is inserted, the numerical aperture (NA) in the width direction is smaller than that in the longitudinal direction by the lens means disposed between the mask means. ) Can be increased, and the condensed shape of the laser beam on the mask is further condensed in the narrow width direction, and the energy density of the laser beam is improved.

(5) According to the fifth aspect of the present invention, the laser beam is dispersed into a plurality of vertically long beams by the homogenizer, so that the beam intensity is made uniform and the light output is controlled. A large number of vertically long beams are condensed by the condenser lens, and a narrow and rectangular laser beam is applied to a predetermined position of the mask. For this reason, the intensity of the laser beam is made uniform and the output is controlled. In addition, unlike the conventional light-collecting characteristics, the laser beam is narrowed so that the numerical aperture NA increases in the width direction narrower than the longitudinal direction. As a result, the energy density of the laser beam is improved, and the same effect as that of the third aspect is also achieved.

[Brief description of the drawings]

FIG. 1 is an overall schematic view showing an embodiment of a laser processing apparatus for processing an ink jet nozzle hole of an ink jet printer according to an embodiment of the present invention.

FIG. 2 is an enlarged schematic view showing a state in which a laser beam condensed by a condenser lens in the processing apparatus of FIG. 1 is further converged in one direction (narrow width direction) by a cylindrical lens and condensed on a mask; It is a top view.

FIG. 3A is an enlarged front view showing a laser beam shape (condensing shape) on a mask before a cylindrical lens is inserted, and FIG. 3B is a cylindrical view in the apparatus of FIG. It is a front view which expands and shows the laser beam shape (condensing shape) on the mask after lens insertion.

FIG. 4 is an overall schematic diagram showing an example of a conventional general laser processing apparatus.

FIG. 5A is a side view for explaining a numerical aperture NA which is a converging angle in a Y direction which is condensed by a condenser lens 9 and irradiated on a mask 11, and FIG. FIG. 3 is a plan view for explaining the numerical aperture NA in the X direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 ・ 3 ・ 4 Total reflection mirror 5 Processing table 6 Laser shaping section 7 Beam expander 8 Fly eye lens (homogenizer) 9 Condenser lens 10 Cylindrical lens 11 Mask 12 Imaging lens 20 Laser processing device A Laser beam B Workpiece

Claims (5)

[Claims] 1. A laser beam oscillator, a beam shaping unit for shaping a laser beam output from the oscillator, a beam expander for expanding the laser beam output from the shaping unit, and a beam expander Laser processing having a homogenizer for homogenizing the output laser beam, and a condenser lens for condensing the laser beam output from the homogenizer into a substantially elongated shape on a mask having a pattern corresponding to a processing shape on a workpiece. In the apparatus, between the condenser lens and the mask, lens means for narrowing an irradiation angle of a laser beam irradiated toward the mask in a narrow width direction of the condensing shape formed on the mask is arranged. A laser processing apparatus characterized in that: 2. A laser processing apparatus according to claim 1, wherein said lens means is a cylindrical lens. 3. A laser beam oscillator, a beam shaping unit for shaping a laser beam output from the oscillator, a beam expander for expanding the laser beam output from the shaping unit, and a beam expander. Laser processing having a homogenizer for homogenizing the output laser beam, and a condenser lens for condensing the laser beam output from the homogenizer into a substantially elongated shape on a mask having a pattern corresponding to a processing shape on a workpiece. In the apparatus, a numerical aperture (NA) of the laser beam focused from the condenser lens toward the mask is increased in a direction having a width smaller than a longitudinal direction of the focused shape formed on the mask. Characteristic laser processing equipment. 4. A laser processing apparatus according to claim 3, wherein lens means is disposed between said condenser lens and said mask. 5. The apparatus according to claim 1, wherein said homogenizer is a fly-eye lens for dispersing a laser beam into a plurality of elongated beams, and said condenser lens focuses said plurality of elongated beams. A laser processing apparatus according to any one of claims 1 to 4.