JP2003334685A - Laser processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser processing apparatus capable of making holes of superior quality on a processed target in case that two scanning optical systems are coped with one processed lens. <P>SOLUTION: One light passage is divided into first and second light passage by a light passage separating means. A laser beam passing through the first light passage is biased by a two-dimensional biassing means 15, and a laser beam passing through the second light passage is also biased by a two-dimensional biassing means 22. Upon integrating the first aid second light passages into one light passage by a polarized beam splitter 25, the laser beam is projected into the processed lens 30. <P>COPYRIGHT: (C)2004,JPO

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 hole processing, cutting and the like by using a laser beam, and in particular, separating a laser beam into a plurality of laser beams and processing each of the separated laser beams on a processing target. Laser processing apparatus for processing holes at different positions.

[0002]

2. Description of the Related Art A laser processing apparatus is an apparatus for processing a hole in, for example, a printed circuit board by using a laser beam.

In order to improve processing efficiency, Japanese Patent Laid-Open No. 11-
In Japanese Patent No. 58055 (hereinafter referred to as “first conventional technology”), N sets (N is a plurality) of two-dimensional scanning optical systems for positioning laser light and processing lenses are provided, and laser light output from a laser oscillator is provided. Is divided into N lines, and the divided laser beams are condensed at different positions on the printed circuit board. In this way, N locations can be processed at the same time, so that work efficiency can be improved. In this case, since the size of the processing area is determined by the size of the processing lens, the processing lenses are arranged at equal intervals and the printed board is placed on the common XY stage. Then, when the processing within a certain processing area is completed, the operation of moving the XY stage and positioning the next processing area with respect to the processing lens is repeated until the processing is completed.

Further, JP-A-11-314188 (hereinafter referred to as "second prior art") and JP-A-2000.
-190087 (hereinafter, referred to as "third prior art"), two scanning optical systems are made to correspond to one processing lens, laser light is divided into two, and two positions are processed at the same time. Improves efficiency.

[0005]

However, in the case of the first prior art described above, N sets of expensive processed lenses are required. Further, in order to utilize N sets of processed lenses, it is necessary to pre-allocate a processing range, and it is also necessary to change the distance between the processed lenses for each processing pattern.

In the second and third prior arts, it is difficult to dispose the two optical scanning optical systems at optimum positions with respect to the processing lens, so that the processing beam is applied to the printed circuit board. It is not possible to make it enter vertically. For this reason, the axis of the processed hole is inclined with respect to the surface of the printed circuit board, which deteriorates the processing quality.

An object of the present invention is to solve the above-mentioned problems in the prior art and, even when two scanning optical systems are made to correspond to one processing lens, it is possible to machine a hole of excellent quality in a processing object. It is to provide a laser processing apparatus.

[0008]

In order to achieve the above-mentioned object, the present invention provides an optical path separating means arranged on the optical path of laser light for separating the optical path into a first optical path and a second optical path, and A first optical path arranged on a first optical path for deflecting the laser light;
Two-dimensional deflecting means, a second two-dimensional deflecting means arranged on the second optical path for deflecting the laser light, and the first
And a processing lens for condensing the laser light deflected by the second two-dimensional deflection means onto a processing target, in the laser processing apparatus, the separated first optical path and second optical path are An optical path unifying means for unifying into one optical path is provided, and the length of the first optical path from the optical path separating means to the optical path unifying means is equal to the length of the second optical path,
The first two-dimensional deflecting means and the second two-dimensional deflecting means are arranged, and the laser light deflected by the first two-dimensional deflecting means and the second two-dimensional deflecting means is converted into one of the laser beams. It is characterized in that it is incident on the processing lens.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) The present invention will be described below based on the illustrated embodiment.

FIG. 1 is a plan view of a laser processing apparatus according to a first embodiment of the present invention, FIG. 2 is a side view, and FIG. 3 is a side view of a polarization beam splitter according to the present invention.

A half-wave plate 2, a mirror 3, an aperture 4, and a beam splitter (BS in FIG. 1) 5 are arranged on the optical path of the laser oscillator 1. On the transmission side of the beam splitter 5, a mirror 6, a mirror 7, a mirror 11, a mirror 14, and a polarization beam splitter (PBS in FIG. 2) 2
5, a relay optical system 26, and a processing lens 30 are arranged. The mirror 8, the mirror 18, and the mirror 21 are arranged on the reflection side of the beam splitter 5. The length of the optical path from the beam splitter 5 to the polarization beam splitter 25 through the mirror 6, the mirror 7, the mirror 11, and the mirror 14 (the beam splitter 5, the mirrors 6, 7,
11 and 14 and the length of the line passing through the centers of the polarization beam splitter 25) and the polarization beam splitter 25 passing from the beam splitter 5 through the mirror 8, the mirror 18, and the mirror 21.
Optical path length (beam splitter 5, mirrors 8, 1
The lengths of the lines passing through the centers of 8 and 21 and the polarization beam splitter 25 are equal to each other.

The laser oscillator 1 oscillates linearly polarized laser light whose electric field oscillates in parallel with the paper surface in a pulse shape. 1 /
The two-wave plate 2 uses birefringence and rotates the polarization direction of the incident laser light by 90 degrees. The beam splitter 5 whose surface is a thin plate separates the transmitted light and the reflected light into a predetermined ratio (here, divided into two) while maintaining the polarization direction of the incident light.

The scanner 9 controls the motor 10 to position the mirror 11 at a designated position. Scanner 1
2 controls the motor 13 to position the mirror 14 at the designated position. Then, the scanner 9 and the scanner 1
2 and 1 constitute the first two-dimensional deflecting means 15.

The scanner 16 controls the motor 17 to
The mirror 18 is positioned at the designated position. The scanner 19 controls the motor 20 to position the mirror 21 at the designated position. Then, the scanner 16 and the scanner 19 constitute a second two-dimensional deflection means 22.

As shown in FIG. 3, the polarization beam splitter 25 has a structure in which a plate-like germanium substrate 51 and a germanium substrate 53 are attached to each other, and a laser output from the laser oscillator 1 is provided on the surface of the germanium substrate 51. A large number of gratings (grooves) 52 having a pitch smaller than the wavelength of light are formed. Reflection is suppressed by the antireflection coating on the opposing sides of the germanium substrates 51 and 53 and the opposite side. Then, the polarization beam splitter 25 transmits the P-polarized component of the incident light (vibration component parallel to the paper surface of FIG. 2) and reflects the S-polarized component (vibration component perpendicular to the paper surface of FIG. 2).

In the relay optical system 26, condenser lenses 27 and 28 having the same focal length are arranged at a distance of twice the focal length. This relay optical system is an afocal system in which, when incident light is parallel light, emitted light is also parallel light, and is called an afocal optical system.

The processed lens 30 is a so-called fθ lens, and a light beam that passes through the front focal point on the optical axis of the lens set at the time of design and is incident at an angle θ with respect to the optical axis of the lens is at the rear focal point of the lens. Plane perpendicular to the optical axis of
It is called the "back focal plane". F) from the optical axis of the lens in
(However, f is the focal length of the processing lens 30.) It is vertically focused. A light ray incident at an angle θ with respect to the optical axis of the lens and deviating from the front focal point is also condensed at a position of fθ from the optical axis of the lens on the rear focal plane. The optical axis of the light is oblique to the back focal plane.

The processing object 31 is mounted on the XY stage 32 so that the upper surface 31a is substantially flush with the back focal plane. The XY stage 32 is movable in the XY directions.

Next, the operation of this embodiment will be described.

The linearly polarized laser light output from the laser oscillator 1 has its polarization plane (electrical scene) adjusted by the half-wave plate 2 in the direction perpendicular to the paper surface, and passes through the mirror 3 and the aperture 4. Illuminate. The laser light that has passed through the opening 4 enters the beam splitter 5, the component parallel to the paper surface passes through the beam splitter 5, and the component perpendicular to the paper surface is reflected. The laser beam that has passed through the beam splitter 5 is deflected by the two-dimensional deflection means 15 including the mirrors 11 and 14 via the mirrors 6 and 7, passes through the polarization beam splitter 25, and then the processed lens 30 via the relay optical system 26. And is focused on the first position of the processing target 31. That is, the opening 4
Image is formed at the first position of the processing object 31. At this time, the two-dimensional deflection means 15 is imaged by the relay optical system 26 in the vicinity of the front focus position of the processing lens 30, so that the axis of the hole processed in the processing object 31 is perpendicular to the upper surface 31a.

On the other hand, the laser beam reflected by the beam splitter 5 is deflected by the two-dimensional deflecting means 22 composed of the mirrors 18 and 21 via the mirror 8 and after being reflected by the polarizing beam splitter 25, the relay optical system 26. The light enters the processing lens 30 via the and is condensed at a second position of the processing target 31 different from the first position. That is, the image of the opening 4 is formed at the second position of the processing target 31. At this time, 2
The three-dimensional deflection means 22 is imaged near the front focus position of the processing lens 30 by the relay optical system 26.
The axis of the hole machined in 1 is perpendicular to the upper surface 31a.

As a result, the processing object 31 can be processed at two positions at the same time, and the laser light which is transmitted through the beam splitter 5 and is incident on the polarization beam splitter 25,
Since the optical paths of the laser beams reflected by the beam splitter 5 and incident on the polarization beam splitter 25 have the same length, holes having the same shape can be formed at the first position and the second position of the processing target 31.

In this embodiment, the aperture 3 is arranged on the front side of the beam splitter 5 (on the laser beam incident side), but the distances to the polarized beam beam splitter 25 are made equal to each other so that the first optical path is formed. Even if an opening is arranged in each of the second optical paths, the same effect as the above case can be obtained.

Further, even when processing is performed at the focal position of the processing lens 30 without providing the opening 3, since the distance from the beam splitter 5 to the polarization beam splitter is the same, the same effect as the above case can be obtained.

When the number of processing points included in the processing area determined by the size of the processing lens 30 is odd, for example, 2
The rotation angle of the mirror 11 of the three-dimensional deflecting means 15 is increased so that the laser light reflected by the mirror 11 deviates from the mirror 14, and the two-dimensional deflecting means 22 positions the laser light at the processing location. It may be performed once in the area.

Next, the polarization beam splitter 25 will be further described.

4A and 4B are views for explaining the arrangement direction of the polarization beam splitter 25 according to the present invention, FIG. 4A is an explanatory view of the incident direction of laser light, and FIG. 4B is a view as seen from the arrow A of FIG. .

The duty ratio α (the width of the portion where the groove is not formed is α) on the surface of germanium having a refractive index of n _Ge.
When the grating 52 having the groove width, that is, the width of the air portion of 1-α) is formed, the refractive index n for light whose electric field vibrates perpendicularly to the grating vector K (direction orthogonal to the grating 52) is ₁ can be approximated by Equation 1, and the equivalent refractive index n ₂ for polarized light whose electric field oscillates in parallel with the grating vector K can be approximated by Equation 2.

[0029]

[Equation 1] Then, from the definition of the polarization, with n ₁ in the refractive index n _p is the formula 1 of the grating portion with respect to the laser beam of the P polarized light incident from the left side and upward to the grating 52 at an incident angle of 45 degrees in FIG. 4 (a), The refractive index n _s of the grating portion for S-polarized light is given by n ₂ in the above equation 2.

Next, a more specific description will be given using numerical values.

For example, n _Ge is 4.0, duty ratio α
When 0.8 is set, n _p = 3.61 and n _s = 1.11. At this time, if the thickness of the grating layer (that is, the depth of the groove) is set to 1/3 of the wavelength λ of the laser light, the reflected lights of P-polarized light interfere with each other, and the reflectance of P-polarized light becomes almost 0. Moreover, since the reflectance of S-polarized light is 0.8 or more, the energy of the laser light is hardly lost.

When a polarization beam splitter capable of making a laser beam incident at an incident angle of 45 degrees is adopted in this way, the outer shape of the optical system can be made small and the alignment work of the optical system can be facilitated. Further, since the optical path length inside the polarization beam splitter 25 can be shortened, it can be arranged close to the processing lens 30. As a result, the relay optical system 26 may be omitted in some cases.

Incidentally, a polarization beam splitter for a carbon dioxide laser which is generally used must have an incident angle of about 75 degrees. Therefore, for the same opening,
Since it is necessary to use a larger one than the polarization beam splitter in this embodiment and the optical path in the transmission direction becomes long, the alignment work becomes complicated.

5A and 5B are views for explaining the arrangement direction of another polarization beam splitter according to the present invention. FIG. 5A is an explanatory view of the incident direction of laser light, and FIG. 5B is a view as seen from the arrow B of FIG. is there.

The polarization beam splitter 25 in this embodiment has right-angle prisms 61 and 6 made of germanium.
2 is attached to the oblique side, and a grating 52 is formed on the inclined surface of the right-angle prism 61 at a pitch smaller than the wavelength of the laser light output from the laser oscillator 1. Reflection is suppressed on the incident surface and the emission surface of the right-angled prisms 61 and 62 other than the facing inclined surfaces by antireflection coating. Then, when the refractive index n _p for P-polarized light is made larger than the refractive index n _s for S-polarized light and the grating 52 is arranged in the direction shown in FIG.
S-polarized light can be totally reflected by the grating portion and P-polarized light can be transmitted. Further, by rotating the direction of the grating 52 by 90 degrees from the position shown in the figure, the P polarized light can be totally reflected by the grating portion and the S polarized light can be transmitted.

As described above, when the polarization beam splitter 25 is composed of two right-angle prisms, the polarized light to be reflected or transmitted can be freely selected, and the reflection angle can be set to some extent, so that the alignment work of the optical system can be performed. It will be easier.

Next, a more specific description will be given using numerical values.

For example, two angles other than the apex angle of the rectangular prism are 45 degrees, n _Ge is 4.0, and the duty ratio α is 0.6.
Then, n _p = 3.16 and n _s = 1.27. Here, if the thickness of the grating layer is 1.15λ, P
The transmittance of polarized light can be approximately 1, and S-polarized light is totally reflected (reflectance of 1). Thus, if the polarization beam splitter 25 is composed of two right angle prisms,
It is possible to make the polarized light separating property more excellent than the plate type.

In this embodiment, the relay optical system 2
Although 6 is arranged between the polarization beam splitter 25 and the processing lens 30, it may be arranged between the processing lens 30 and the processing object 31.

(Second Embodiment) FIG. 6 is a side view of a laser processing apparatus according to a second embodiment of the present invention. Components having the same functions or functions as those in FIG. 2 are designated by the same reference numerals. The description is omitted. The plan view is the same as that of the first embodiment.

The relay optical system 40 is composed of a lens 41, a lens 42 and a lens 28. Lens 4
1, the polarization beam splitter 25 is arranged at the intersection of the optical axes of the lens 42 and the lens 28.

In the case of this embodiment, the two-dimensional deflection means 22
The image of (2) is formed near the front focus of the processing lens 30 by the lens 42 and the lens 28 via the polarization beam splitter 25. In addition, the image of the two-dimensional deflecting means 15 is formed by the lens 41 and the lens 28 via the polarization beam splitter 25.
An image is formed near the front focus of the processing lens 30. In addition, in this embodiment, by disposing the polarization beam splitter 25 while avoiding the focal positions of the lenses 41 and 42,
The polarization beam splitter 25 is prevented from being damaged by heating.

With this structure, the two-dimensional deflecting means 15 and 22 and the lenses 41 and 42 can be physically brought close to each other, so that the relay optical system in the laser processing apparatus can be easily arranged and the optical system can be improved. The system can be miniaturized and inexpensively constructed.

As the polarization beam splitter 25,
A plate-type or cube-type polarization beam splitter using a commonly available dielectric multilayer film can be used. Further, it is possible to use a beam splitter which does not have polarization characteristics, although the power utilization efficiency is poor.

By the way, in the first and second embodiments, the laser light is divided at the same time, but it may be divided in time.

(Third Embodiment) FIG. 7 is a plan view of a laser processing apparatus according to a third embodiment of the present invention. Components having the same functions or functions as those in FIG. 1 are designated by the same reference numerals. The description is omitted. The side view of the laser processing apparatus according to the third embodiment is the same as FIG. 2 of the first embodiment.

The linearly polarized laser light whose electric field output from the laser oscillator 1 oscillates in parallel with the paper surface is deflected by the mirror 89 in the upward direction (Z axis positive direction), and then the mirror 90.
Is deflected in the right direction (X-axis positive direction), and the vibrating surface enters the acousto-optic element (AO element) 91 in a direction perpendicular to the paper surface. The acousto-optic element 91 is a device that can adjust the diffraction angle of incident light by changing the drive frequency. Therefore, by driving the acoustooptic element 91 with two different frequencies, the laser light can be distributed in a predetermined direction. Then, one of the distributed laser beams is passed through the mirrors 92 and 93 to the two-dimensional deflecting means 15 not shown, and the other is passed through the mirrors 94 and 95 to the two-dimensional deflecting means 22 not shown.
Incident on.

As described above, when the laser beam is temporally divided into two by the acousto-optic element 91 which replaces the beam splitter 5 in FIG. 1, the repetition frequency of pulse emission of the laser oscillator 1 is substantially doubled. The efficiency can be improved. Even if it is not allowed to irradiate the laser beam with the highest repetition frequency due to the characteristics of the object to be processed, it is possible to improve the processing efficiency by distributing the laser beam to different processing positions. If the pulse width of the laser light is larger than the width required for processing,
Since it is possible to generate and process, for example, two pulses from one pulse, it is possible to improve the processing efficiency even when the pulse emission repetition frequency of the laser oscillator 1 is low.

[0049]

As described above, according to the present invention,
An optical path separating means arranged on the optical path of the laser light for separating the optical path into a first optical path and a second optical path, and a first two-dimensional deflecting means arranged on the first optical path for deflecting the laser light. And a second two-dimensional deflecting means arranged on the second optical path for deflecting the laser light, and the laser light deflected by the first and second two-dimensional deflecting means on a processing target. In a laser processing device including a processing lens that emits light,
An optical path unifying means for unifying the separated first optical path and second optical path into one optical path is provided, and the length of the first optical path from the optical path separating means to the optical path integrating means and the second optical path. The first two-dimensional deflection means and the second two-dimensional deflection means are arranged so that the optical paths have the same length, and the first two-dimensional deflection means and the second two-dimensional deflection means deflect the light. Since the generated laser light is made incident on one of the processing lenses, even when the two scanning optical systems correspond to one processing lens, it is possible to process a hole having excellent quality on the processing target.

[Brief description of drawings]

FIG. 1 is a plan view of a laser processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a side view of the laser processing apparatus according to the first embodiment of the present invention.

FIG. 3 is a side view of a polarization beam splitter according to the present invention.

FIG. 4 is a diagram illustrating an arrangement direction of a polarization beam splitter according to the present invention.

FIG. 5 is a diagram illustrating an arrangement direction of another polarization beam splitter according to the present invention.

FIG. 6 is a side view of a laser processing apparatus according to a second embodiment of the present invention.

FIG. 7 is a plan view of a laser processing apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

15 Two-dimensional deflection means 22 Two-dimensional deflection means 25 Polarizing beam splitter 30 Processing lens

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Aoyama             Hitachi Bi, 2100 Kamiimazumi, Ebina City, Kanagawa Prefecture             Inside Amechanics Co., Ltd. F-term (reference) 2H099 AA17 BA17 CA17                 4E068 AF01 CA05 CD02 CD04 CD08                       CD10 DA11

Claims (5)

[Claims] 1. An optical path separating means arranged on an optical path of laser light for separating the optical path into a first optical path and a second optical path; and a first optical path arranged on the first optical path for deflecting the laser light.
Two-dimensional deflecting means, a second two-dimensional deflecting means arranged on the second optical path for deflecting the laser light, and the first
And a processing lens that condenses the laser light deflected by the second two-dimensional deflection means onto a processing target, wherein the separated first optical path and second separated optical path are combined into one. An optical path integrating means for integrating the optical path is provided, and the first path from the optical path separating means to the optical path integrating means is provided.
The first two-dimensional deflecting means and the second two-dimensional deflecting means are arranged such that the optical path length of the second optical path and the optical path length of the second optical path are equal to each other. A laser processing apparatus, characterized in that the laser light deflected by a second two-dimensional deflection means is made incident on one processing lens. 2. An opening arranged on the optical path of the laser light for regulating the outer shape of the laser light, an optical path separating means for separating the optical path into a first optical path and a second optical path, and on the first optical path. And a second two-dimensional deflecting means disposed on the second optical path for deflecting the laser light, and first and second two-dimensional deflecting means disposed on the second optical path. A laser processing apparatus comprising: a processing lens for condensing the laser light deflected by a two-dimensional deflection means onto an object to be processed, wherein the separated first optical path and second optical path are integrated into one optical path. An optical path integrating means is provided, and the first two-dimensional deflecting means and the second optical path are arranged so that the length of the first optical path from the opening to the optical path integrating means is equal to the length of the second optical path. A two-dimensional deflecting means is provided, and the first two-dimensional deflecting means and And the laser beam deflected by the second two-dimensional deflecting means is made incident on one of the processing lenses. 3. The laser processing apparatus according to claim 1, wherein a relay optical system is provided, and the relay optical system is arranged between the optical path integrating means and the processing target. 4. The laser processing apparatus according to claim 3, wherein the relay optical system is an afocal optical system. 5. The laser processing apparatus according to claim 1, wherein the optical path unifying unit is a polarization beam splitter including a grating.