JP4074217B2 - Lens protection member for laser processing machine and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is, for example, a method of manufacturing a lens protecting member Zai及 patron to protect the condenser lens carbon dioxide gas laser processing machine.
[0002]
[Prior art]
In general, in a laser beam machine such as a carbon dioxide laser beam machine, in order to protect the condenser lens from dust generation, contamination by sputtering, and damage during processing, for example, between a workpiece such as a printed wiring board and the condenser lens. A lens protection member (lens protection window) is disposed on the screen.
A conventional lens protection member is configured by forming an antireflection film (AR coating) on both surfaces of a flat substrate that transmits laser light. Moreover, as a material of the base material, for example, ZnSe or Ge is used. Furthermore, the antireflection film is formed of a multilayer film made of, for example, ThF ₄ , YF ₄ , ZnS, Ge, ZnSe, or the like (for example, see Non-Patent Document 1).
[0003]
[Non-Patent Document 1]
"Laser beam measurement and optical component evaluation technology", March 1991, Laser Thermal Processing Study Group Working Group, p. 105 and p. 121
[0004]
[Problems to be solved by the invention]
In the conventional lens protection member as described above, a material such as ThF ₄ , YF ₄ , ZnS, and ZnSe that reacts with an acid is used for the antireflection film. In contrast, when processing a printed wiring board made of a resin material such as epoxy, dust and gas containing bromine and the like are generated, so the antireflection film on the laser light emission side is corroded by bromic acid, It becomes easy to peel off. As described above, when the antireflection film on the laser beam emitting side is peeled off, for example, when Ge is used as the base material, about 36% of the laser beam is reflected, and only about 64% reaches the workpiece. I will not. In addition, the reflected laser light returns to the condensing lens and the laser oscillator, and there is a possibility that the optical components in the condensing lens and the laser oscillator are damaged.
[0005]
The present invention has been made in order to solve the above-mentioned problems, and a lens protection member for a laser beam machine capable of improving corrosion resistance while keeping the reflectance of laser light low, and its It aims at obtaining a manufacturing method.
[0006]
[Means for Solving the Problems]
Lens protection member of the laser processing machine according to the invention includes a first surface which is the laser beam incident surface, an emitting surface of the laser light and a second surface opposite to the workpiece, transmits the laser beam And a diamond-like carbon film formed directly on the second surface. The antireflection film is formed on the first surface and prevents reflection of laser light.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a main part of an infrared laser beam machine according to Embodiment 1 of the present invention. In the figure, a laser oscillator 1 is disposed to face a workpiece 2 such as a printed wiring board. A condensing lens 3 is disposed between the laser oscillator 1 and the workpiece 2. Here, a carbon dioxide laser with a wavelength of 10.6 μm is used as the laser beam 6 emitted from the laser oscillator 1, and a single lens made of ZnSe is used as the condenser lens 3.
[0008]
A lens protection member as a laser transmitting member that transmits the laser beam 6 between the condenser lens 3 and the workpiece 2 and protects the condenser lens 3 from dust generation and contamination due to sputtering and damage during processing. 4 is arranged. The condenser lens 3 and the lens protection member 4 are held in a cylindrical barrel 5.
[0009]
The lens protection member 4 includes a flat substrate 7, an antireflection film 8, and a diamond-like carbon film 9. The base material 7 has a first surface 7a and a second surface 7b parallel to each other, and is made of a laser transmitting material such as Ge. Here, the first surface 7 a is an incident surface for the laser light 6, and the second surface 7 b is an emission surface for the laser light 6.
[0010]
The antireflection film 8 is formed on the first surface 7 a by, for example, vacuum deposition, and prevents reflection of the laser light 6 incident on the base material 7. The antireflection film 8 is formed of a multilayer film composed of a plurality of layers having different refractive indexes, such as YF ₄ , ZnS, and Ge. Further, the reflectance of the laser beam 6 in the antireflection film 8 is preferably 3% or less, particularly preferably 1% or less.
[0011]
The diamond-like carbon film 9 is formed on the second surface 7b by, for example, plasma CVD. Diamond-like carbon is a material that has hardness similar to diamond, has excellent resistance to acid corrosion, and transmits light in the infrared region. Further, the reflectance of the laser beam 6 in the diamond-like carbon film 9 is about 5%.
[0012]
Next, FIG. 2 is a process diagram showing a manufacturing method of the lens protection member 4 of FIG. First, as shown in FIG. 2A, a disk-shaped substrate 7 made of Ge is prepared. Next, as shown in FIG. 2B, the first surface 7a of the substrate 7 is polished into a convex shape, and the second surface 7b is polished into a concave shape. The cross-sectional shapes of the concave surface and the convex surface are very gentle arc shapes. For example, when a substrate 7 having a thickness of 5 mm and a diameter of 105 mm is used, the height or depth of the central portion with respect to the peripheral portion is about 2 to 3 μm. It is. However, in order to facilitate understanding, in FIG. 2, the polishing amount is drawn large.
[0013]
Next, a diamond-like carbon film 9 is formed on the second surface 7b by plasma CVD or the like. The thickness of the diamond-like carbon film 9 is, for example, about 1 μm. In the diamond-like carbon film 9 thus formed, an internal stress that tends to spread to the periphery is generated.
[0014]
Therefore, when the diamond-like carbon film 9 is formed on one surface of the base material 7, the base material 7 is deformed into a flat plate shape as shown in FIG. 7a and the 2nd surface 7b become a plane (flatness becomes high). In other words, the concave surface and the convex surface are processed in advance so that the first surface 7a and the second surface 7b become flat (a flat surface with sufficient flatness for use) by the internal stress of the diamond-like carbon film 9. Keep it.
[0015]
Thereafter, the antireflection film 8 is formed on the flat first surface 7a by, for example, vacuum deposition. At this time, since the internal stress of the antireflection film 8 is small, there is almost no deformation of the base material 7, and the flatness of the surface of the antireflection film 8 and the surface of the diamond-like carbon film 9 (the height of the central portion relative to the peripheral portion or (Depth) can be set to about 0.7 μm.
[0016]
In the infrared laser processing machine using the lens protection member 4 as described above, the diamond-like carbon film 9 is formed on the surface of the lens protection member 4 facing the workpiece 2, thereby improving the corrosion resistance. It is possible to prevent a decrease in reflectance due to film peeling.
[0017]
Further, while the reflectance of the laser beam 6 in the antireflection film 8 is about 1%, the reflectance of the diamond-like carbon film 9 is about 5%, but the diamond-like carbon film 9 is formed on both surfaces of the substrate 7. The reflectance can be kept sufficiently low as compared with the case of forming. This sufficiently suppresses the laser light 6 from returning to the condensing lens 3 and the laser oscillator 1 and prevents damage to the relatively expensive condensing lens 3 and optical components in the laser oscillator 1. it can.
[0018]
Further, before the diamond-like carbon film 9 is formed, the first surface 7a is polished into a convex shape, and the second surface 7b is polished into a concave shape. Since the substrate 7 is deformed using internal stress and the first surface 7a and the second surface 7b are flat, the diamond-like carbon film 9 is formed only on one surface, but the wavefront of the laser beam 6 is Disturbance can be prevented from occurring, and deterioration in processing quality can be prevented.
[0019]
Here, when a hole having a diameter of about 200 μm and a depth of about 100 μm was processed on a printed wiring board by an infrared laser processing machine having the lens protection member 4 of Embodiment 1, the processing shape was lost due to distortion of the lens protection member 4. As a result, good processing was possible.
[0020]
Further, the lens protection member 4 was disposed in the vicinity of the printed wiring board, the laser output was set to 30 W, and a hole having a diameter of about 300 μm and a depth of about 150 μm was continuously processed (about 100 hours) on the printed wiring board. At this time, the diamond-like carbon film 9 is exposed to a large amount of dust and gas, but the diamond-like carbon film 9 is not peeled off, and the optical system in the condenser lens 3 and the laser oscillator 1 is also damaged. There wasn't.
[0021]
Comparative Example 1
Next, FIG. 3 is a process diagram showing a method for manufacturing a lens protection member according to Comparative Example 1. In Comparative Example 1, as the base material 7 as shown in FIG. 3A, a material having a diameter of 105 mm and a thickness of 5 mm and made of Ge was used. The first surface 7a and the second surface 7b were previously processed so as to have a flatness of about 0.4 μm.
[0022]
Thereafter, a diamond-like carbon film 9 was formed on the first surface 7 a of the substrate 7. Thereby, the base material 7 was deformed as shown in FIG. That is, the flatness of the surface of the diamond-like carbon film 9 was about 3 μm.
[0023]
Thereafter, a diamond-like carbon film 9 was also formed on the second surface 7b of the base material 7 in the same manner as the first surface 7a side. As a result, the deformation of the base material 7 was corrected, and the flatness of the surface of the diamond-like carbon film was about 0.7 μm.
[0024]
When such a lens protection member is replaced with the lens protection member 4 in FIG. 1 and a hole having a diameter of about 200 μm and a depth of about 100 μm is formed on a printed wiring board, the deformation of the processed shape due to distortion of the lens protection member is not seen. Good processing was possible.
[0025]
Further, the lens protection member was disposed in the vicinity of the printed wiring board, the laser output was set to 30 W, and a hole having a diameter of about 300 μm and a depth of about 150 μm was continuously processed (about 100 hours) on the printed wiring board. At this time, the diamond-like carbon film 9 was exposed to a large amount of dust and gas, but the diamond-like carbon film 9 was not peeled off. However, the reflected light from the diamond-like carbon film 9 on the first surface 7a side caused damage to the condensing lens 3 and the optical system in the laser oscillator 1.
[0026]
Comparative Example 2
Next, FIG. 4 is a process diagram showing a method for manufacturing a lens protection member according to Comparative Example 2. In Comparative Example 2, as the base material 7 as shown in FIG. 4A, a material having a diameter of 105 mm and a thickness of 5 mm and made of Ge was used. The first surface 7a and the second surface 7b were previously processed so as to have a flatness of about 0.4 μm.
[0027]
Thereafter, as shown in FIG. 4B, an antireflection film 8 was formed on the first surface 7a. Further, as shown in FIG. 4C, an antireflection film 8 was also formed on the second surface 7b. Since the internal stress of the antireflection film 8 was sufficiently small, there was no change in flatness.
[0028]
When such a lens protection member is replaced with the lens protection member 4 in FIG. 1 and a hole having a diameter of about 200 μm and a depth of about 100 μm is formed on a printed wiring board, the deformation of the processed shape due to distortion of the lens protection member is not seen. Good processing was possible.
[0029]
Further, the lens protection member was disposed in the vicinity of the printed wiring board, the laser output was set to 30 W, and a hole having a diameter of about 300 μm and a depth of about 150 μm was continuously processed (about 100 hours) on the printed wiring board. At this time, since the antireflection film 8 was exposed to a large amount of dust and gas, the antireflection film 8 was peeled off. And the condensing lens 3 was damaged by the reflected light from the part where the antireflection film 8 was peeled off.
[0030]
Comparative Example 3
Next, FIG. 5 is a process diagram showing a method for manufacturing a lens protection member according to Comparative Example 3. In Comparative Example 3, as the base material 7 as shown in FIG. 5A, a material having a diameter of 105 mm and a thickness of 5 mm and made of Ge was used. The first surface 7a and the second surface 7b were previously processed so as to have a flatness of about 0.4 μm.
[0031]
Thereafter, as shown in FIG. 5B, an antireflection film 8 was formed on the first surface 7 a of the substrate 7. At this time, since the internal stress of the antireflection film 8 was small, the flatness did not change. Thereafter, a diamond-like carbon film 9 was formed on the second surface 7b. As a result, the substrate 7 was deformed as shown in FIG. That is, the flatness of the surface of the antireflection film 8 and the surface of the diamond-like carbon film 9 was about 3.0 μm.
[0032]
When such a lens protection member is replaced with the lens protection member 4 in FIG. 1 and a hole having a diameter of about 200 μm and a depth of about 100 μm is processed on a printed wiring board, the processing shape is broken due to distortion of the lens protection member. Good processing could not be performed.
[0033]
Thus, according to the lens protection member 4 of the first embodiment, compared to the lens protection members of Comparative Examples 1 to 3, the corrosion resistance can be improved while keeping the reflectance of the laser light 6 low. Moreover, distortion due to internal stress of the diamond-like carbon film 9 can also be prevented.
[0034]
Embodiment 2. FIG.
Next, FIG. 6 is a process diagram showing a method for manufacturing a lens protection member according to Embodiment 2 of the present invention. First, as shown in FIG. 6A, a disk-shaped base material 7 made of Ge is prepared. Next, as shown in FIG. 6B, the second surface 7b of the substrate 7 is polished into a concave shape. The cross-sectional shape of the concave surface is a very gentle arc shape. For example, when the base material 7 having a thickness of 5 mm and a diameter of 105 mm is used, the height or depth of the central portion with respect to the peripheral portion is about 2 to 3 μm. However, for easy understanding, FIG. 6 shows a large amount of polishing.
[0035]
Next, a diamond-like carbon film 9 is formed on the second surface 7b by plasma CVD or the like. The thickness of the diamond-like carbon film 9 is, for example, about 1 μm. In the diamond-like carbon film 9 thus formed, an internal stress that tends to spread to the periphery is generated.
[0036]
Therefore, when the diamond-like carbon film 9 is formed on one surface of the base material 7, the base material 7 is deformed as shown in FIG. 6C by the internal stress of the diamond-like carbon film 9, and the second surface 7b is flat. (A flat surface with sufficient flatness for use). Thereby, the flatness of the surface of the diamond-like carbon film 9 is about 0.7 μm.
[0037]
Thereafter, the first surface 7a is polished so that the flatness is about 0.4 μm. Then, the antireflection film 8 is formed on the flat first surface 7a by, for example, vacuum deposition. At this time, since the internal stress of the antireflection film 8 is small, the base material 7 is hardly deformed, and the flatness of the antireflection film 8 and the diamond-like carbon film 9 is maintained.
[0038]
When such a lens protection member is replaced with the lens protection member 4 in FIG. 1 and a hole having a diameter of about 200 μm and a depth of about 100 μm is formed on a printed wiring board, the deformation of the processed shape due to distortion of the lens protection member is not seen. Good processing was possible.
[0039]
Further, the lens protection member was disposed in the vicinity of the printed wiring board, the laser output was set to 30 W, and a hole having a diameter of about 300 μm and a depth of about 150 μm was continuously processed (about 100 hours) on the printed wiring board. At this time, the diamond-like carbon film 9 is exposed to a large amount of dust and gas, but the diamond-like carbon film 9 is not peeled off, and the optical system in the condenser lens 3 and the laser oscillator 1 is also damaged. There wasn't.
[0040]
Furthermore, when the hole was drilled to the printed wiring board with a diameter of 60 μm and a depth of 30 μm using the lens protection member obtained in the second embodiment, the deformation of the processing shape due to the distortion of the lens protection member was not seen and good. Processing was possible.
[0041]
Thus, according to the manufacturing method of Embodiment 2, the corrosion resistance can be improved while keeping the reflectance of the laser beam 6 low. Further, the flatness on the antireflection film 8 side can be increased more reliably, and the deformation of the processed shape due to the distortion of the lens protection member can be more reliably prevented.
[0042]
In addition, in the manufacturing method of Embodiment 1, 2, when processing the 2nd surface which forms a diamond-like carbon film | membrane into a concave shape, the curvature radius of the cross section of the concave shape is 1500 mm (flatness with respect to a diameter of 100 mm) 0.8 μm) or more is preferable, and in particular, 3000 mm (flatness 0.4 μm with respect to a diameter of 100 mm) or more is desirable.
In the first and second embodiments, the lens protection member has been described. However, the laser transmission member is not limited to the lens protection member, and the present invention can be applied to a laser transmission member used for other purposes.
[0043]
【The invention's effect】
As described above, the lens protection member of the laser beam machine according to the present invention forms the antireflection film for preventing the reflection of the laser beam on the first surface of the base material, and the diamond on the second surface of the base material. Since the like carbon film is formed, the corrosion resistance can be improved while keeping the reflectance of the laser light low.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a main part of an infrared laser beam machine according to Embodiment 1 of the present invention.
2 is a process diagram illustrating a method for manufacturing the lens protection member of FIG. 1. FIG.
3 is a process diagram illustrating a method for manufacturing a lens protection member according to Comparative Example 1. FIG.
4 is a process diagram illustrating a method for manufacturing a lens protection member according to Comparative Example 2. FIG.
5 is a process diagram illustrating a method for manufacturing a lens protection member according to Comparative Example 3. FIG.
FIG. 6 is a process diagram showing a method for manufacturing a lens protection member according to Embodiment 2 of the present invention.
[Explanation of symbols]
4 lens protective member (laser transmitting member), 6 laser light, 7 base material, 7a first surface, 7b second surface, 8 antireflection film, 9 diamond-like carbon film.

Claims (2)

Has a first surface which is the laser beam incident surface, an exit surface of the laser beam and a second surface opposite to the workpiece, flat base material which transmits the laser beam,
An antireflection film that is formed on the first surface and prevents reflection of the laser light, and a diamond-like carbon film that is directly formed on the second surface . Lens protection member . Concave first surface is a plane of incidence of the laser beam, the second surface of a flat substrate that transmits a laser beam and a second surface opposite to the emission surface a and the workpiece the laser light Process to shape,
Forming a diamond-like carbon film on the second surface, thereby deforming the substrate to make the second surface flat;
A method of manufacturing a lens protection member for a laser beam machine, comprising: processing the first surface into a flat surface; and forming an antireflection film for preventing reflection of the laser light on the first surface. .

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