JP4554835B2 - Mold for glass and method for producing glass molded product - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molding die used for producing a high-precision optical element such as an aspheric lens or a glass substrate having a planar pattern of fine irregularities formed on the surface thereof by press molding. Concerning.
[0002]
[Prior art]
2. Description of the Related Art In recent years, when manufacturing optical elements such as lenses and prisms, a method of press-molding a glass material that has been heated and softened using a mold has been widely used. When a highly accurate optical component is manufactured using such a mold, it is necessary to process the mold surface (molded surface) with high shape accuracy and to apply a mirror finish to the mold surface. For this reason, cemented carbide or ceramics has been conventionally used for the base material portion of the mold. Furthermore, in order to protect the mold surface for the purpose of preventing the glass from fusing to the mold surface and preventing oxidation, generally, various coatings are applied to the mold surface.
[0003]
(Problems of conventional technology)
Conventionally, since the material used for the base material part of a shaping | molding die is a very hard and brittle material, the process is performed by grinding and grinding | polishing.
[0004]
When a conventional material is used for the base material portion, it is relatively easy to uniformly process an aspheric surface, a cylindrical surface, a toric surface, and the like. However, for example, a pattern composed of fine irregularities used in a diffraction grating, a hard disk, an MO disk, and the like cannot be processed by grinding because there is no diamond wheel for processing, and photolithography was used. Even in etching, it is difficult to process fine grooves with required dimensional accuracy due to the characteristics of the base material.
[0005]
In addition, even a forming die for forming the core of the waveguide requires groove processing of several μm square. Since this groove is formed in a complicated planar pattern, the groove processing is difficult by the conventional processing method.
[0006]
In addition, a plating layer that is relatively easy to machine is provided on the base material of the mold, and a fine grating is formed on the plating layer to form a pattern such as a diffraction grating. There has been proposed a method of coating a release film. However, even in this method, since the grooves are processed using a diamond tool, there are limits to the width and depth of the grooves that can be processed, the types of patterns that can be formed, and the surface roughness of the mold surface. For example, a groove with a width of several μm can be formed, but the pattern is limited to a simple one.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the problems associated with the conventional molds as described above. The object of the present invention is to provide a high-precision optical element such as an aspheric lens and a flat surface with fine irregularities on the surface. It is an object of the present invention to provide a mold that enables a glass substrate or the like on which a typical pattern is formed to be manufactured by a press molding method.
[0008]
[Means for Solving the Problems]
The glass mold of the present invention is a glass mold used when a molded product is produced by press-molding a glass material that has been softened by heating, and the base material portion is made of quartz glass. It is characterized by that.
[0009]
Preferably, a mold release film is coated on the mold surface of the glass mold.
[0010]
In addition, when manufacturing the glass substrate in which the pattern which consists of fine unevenness | corrugation was formed on the surface using the said glass shaping | molding die, the pattern corresponding to a type | mold surface can be formed using the technique of photolithography. it can.
[0011]
Further, the method for producing a glass molded product of the present invention is a method for producing a molded product by press-molding a glass material heated and softened using a molding die, and the base material portion thereof is used as the molding die. Is characterized by using a mold made of quartz glass.
[0012]
The characteristics of the glass mold according to the present invention will be described.
[0013]
Unlike other general optical glasses, quartz glass has a single composition and therefore has a high melting point. For this reason, quartz glass hardly deforms in a temperature range of 500 ° C. to 800 ° C. in which a normal glass molded product is press-formed. Further, when a lens molding die is manufactured, the die surface can be processed with high accuracy by conventional grinding and polishing. Furthermore, when a pattern is formed on the mold surface with fine irregularities, a photolithography technique for quartz glass has been established, so that various patterns can be formed with high accuracy relatively easily.
[0014]
Therefore, by forming the base material portion of the glass mold with quartz glass, it is possible to mold an optical element or a glass substrate in which a pattern is formed on the surface by unevenness having a width, depth, or height of about several μm. This mold can be manufactured with high shape accuracy.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the example of the shaping | molding die for glass based on this invention is demonstrated using drawing.
[0016]
(Example 1)
FIG. 1 shows a schematic diagram of a mold for molding a lens. In this mold 10, a base material portion 11 is made of quartz glass, and a platinum alloy is coated on the mold surface as a release film 12 with a thickness of 0.3 μm.
[0017]
This mold 10 was attached to the press molding machine shown in FIG. 2, and an optical lens having a diameter of about 12 mm and a thickness of about 5 mm was manufactured by press molding. In FIG. 2, 21 is a fixed shaft, 22 is a moving shaft, 23 is an upper mold unit, 24 is a lower mold unit, 25 is a transparent quartz tube, and 26 is an infrared lamp unit.
[0018]
Low molding glass (L-BAL42; manufactured by OHARA) was used as a molding material, and press molding was performed at a molding temperature of 570 ° C. and a pressing force of 800 kgf. When 500 lenses were continuously molded and the surface accuracy was measured, the average value was about 0.3 μm. Further, even after molding 500 lenses, no particular change was observed on the mold surface, and it was confirmed that the mold surface had sufficient durability.
[0019]
(Example 2)
FIG. 3 shows a manufacturing process of a forming die used when forming a glass substrate on which a pattern is formed by fine rib-shaped protrusions.
[0020]
a. A quartz glass substrate 31 is prepared, and a tungsten thin film 32 as an etching mask is deposited thereon by the PVD method (FIG. 3A).
[0021]
b. A photoresist film 33 is applied on the tungsten thin film 32 by using a spin coater (FIG. 3B).
[0022]
c. Using a photomask 35 on which a predetermined pattern is formed, the photoresist film 33 is irradiated with ultraviolet rays as a photosensitive light beam from above the photomask 35 to expose the photoresist film 33 (FIG. 3C).
[0023]
d. The photosensitive portion of the photoresist film 33 is removed with a solvent (FIG. 3D).
[0024]
e. Ion sputtering is performed from above the photoresist film 33 using argon ions as a medium for selectively removing the etching mask, and the tungsten thin film 32 is removed at the portion where the photoresist film 33 has been removed first. (FIG. 3E).
[0025]
f. The remaining photoresist film 33 is removed by ashing (FIG. 3F).
[0026]
g. Using the tungsten thin film 32 thus patterned as a mask, dry etching is performed using a CF-based gas to etch the surface of the quartz glass substrate 31 (FIG. 3G). At this time, the depth of the groove to be formed can be controlled by adjusting the etching time.
[0027]
h. Ion sputtering using argon ions is performed to remove the remaining tungsten thin film 32 (FIG. 3H). As a result, a pattern with fine grooves is formed on the surface of the quartz glass substrate 31.
[0028]
i. Finally, a platinum alloy is coated on the surface of the quartz glass substrate 31 with a thickness of 0.3 μm by the PVD method as the release film 37 (FIG. 3I).
[0029]
Using the above method, a mold having a predetermined pattern formed on the surface by grooves having a depth of 3 μm and a width of 3 μm was manufactured. This mold was attached to the press molding machine shown in FIG. 2, and a glass substrate having a width of about 10 mm × 10 mm and a thickness of about 1 mm was manufactured under the following conditions.
[0030]
Low molding glass (L-BAL42; manufactured by OHARA) was used as a molding material, and press molding was performed at a molding temperature of 570 ° C. and a pressing force of 800 kgf. When 500 glass substrates were continuously formed and the height of the rib-like protrusions formed on the surface was measured, the height was approximately 3 μm, and sufficient transferability was confirmed. Moreover, even after molding 500 glass substrates, no particular change was observed on the mold surface, and it was confirmed that the mold surface had sufficient durability.
[0031]
【The invention's effect】
According to the glass mold of the present invention, the base material portion of the mold is made of quartz glass. As a result, an optical element and a glass substrate having a pattern with fine irregularities on the surface can be obtained with high shape accuracy and low. It becomes possible to manufacture at a cost.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a glass mold according to the present invention.
FIG. 2 is a diagram showing an outline of a press molding machine in which a glass mold is used.
FIGS. 3A and 3B are diagrams showing an example of a manufacturing process of a glass mold according to the present invention, and FIGS.
[Explanation of symbols]
10 ... Mold,
11 ... base material part,
12 ... release film,
21 ... fixed shaft,
22 ... movement axis,
23 ... Upper mold unit,
24 ... Lower mold unit,
25 ... Transparent quartz tube,
26: Lamp unit,
31 ... quartz glass substrate,
32 ... tungsten thin film,
33 ... Photoresist film,
35 ... Photomask,
37 ... Release film.

Claims (4)

  A mold for glass used when press-molding a glass material that has been softened by heating to produce a molded product, and a pattern consisting of fine irregularities on the surface of a base material part made of quartz glass Is formed by photolithography, a glass mold.   The mold for glass according to claim 1, wherein a mold release film is coated on the mold surface.   A method for producing a molded product by press-molding a glass material softened by heating using a molding die, wherein the molding die is formed from fine irregularities on the surface of a base material portion made of quartz glass. A method for producing a glass molded product, comprising using a mold having a pattern formed by photolithography.   The method for producing a glass molded product according to claim 3, wherein a mold having a mold surface coated with a release film is used as the mold.

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