Glass manufacturing – Apparatus made of special material – Metal-nonmetal composite
Reexamination Certificate
1998-12-14
2002-03-12
Vincent, Sean (Department: 1731)
Glass manufacturing
Apparatus made of special material
Metal-nonmetal composite
Reexamination Certificate
active
06354111
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a press-forming die for glass elements. In particular, the present invention relates to a die for press-forming glass elements, which makes it possible to form and process glass elements for an optical IC with excellent die release performance.
2. Description of the Related Art
A method for press-forming glass elements by means of a press-forming process has been hitherto used. In general, such a method raises several issues including, for example, the die release performance between the glass element and the forming die after the forming process, the surface roughness of the glass element, and the surface quality such as whether or not any scratch exists. Various countermeasures have been investigated, including, for example, the forming condition and the selection of the material for the forming die.
Highly accurate forming operation is required especially when an optical lens is produced. Further, the material for the die raises several issues including the deterioration of die release performance resulting from the reactivity with glass during the forming process at a high temperature, and the surface scratch on the glass-pressing surface. As a solution for such issues, the following technique has been disclosed. That is, in order to make the surface roughness of the formed optical lens to be several hundredth &mgr;m, a die is used, in which a cemented carbide is used as a base material, and a noble metal thin film, which contains a major component of iridium, is formed in a degree of several &mgr;m on the surface of the cemented carbide (see Japanese Laid-Open Patent Publication No. 61-256931). According to this technique, the forming condition of this method is such that lead oxide glass is used as a lens material, the heating temperature is 630° C., the press operation is performed for 2 minutes at a press pressure of 40 kg/cm
2
, and the open process temperature after cooling is 380° C.
On the other hand, for example, when a glass element for optical IC is press-formed and processed, the excellent die release performance is an important factor as well in the same manner as in the forming process for the optical lens. However, the highly accurate operation is not necessarily required concerning the surface scratch, i.e., the processing accuracy of the die. Usually, when the die is subjected to grinding processing by using a diamond grinding wheel, it is inevitable (in view of the processing technique) that the surface roughness of about 0.5 &mgr;m remains at most. However, the surface roughness of this degree is within the allowable range when the product is used for the glass element for optical IC.
When the glass element for optical IC is press-formed and processed, the type of the glass material is selected and used depending on the use or application of the glass element for optical IC. The forming condition is different from those used for processing the optical lens as described above. In general, the forming operation for the glass element for optical IC is performed at a high temperature and at a high pressure, in which the press time is short. Further, the glass element for optical IC is used such that V-shaped grooves are formed on the glass substrate by means of the forming operation, and a glass fiber is positioned and arranged in the grooves. In such a case, the glass fiber is fixed by using an adhesive. It is also necessary to consider the adhesive performance during such a process.
SUMMARY OF THE INVENTION
The present invention has been made taking such problems into consideration, an object of which is to provide a die for press-forming glass elements, to be used to produce the glass elements by means of the press-forming process by using a variety of glass materials appropriately selected depending on the use or application of the glass elements, in which an appropriate degree of surface roughness of the glass element is ensured, the die release performance is excellent, and the adhesive performance for an adhesive is also excellent when a glass fiber is arranged in V-shaped grooves formed on a glass substrate.
According to the present invention, there is provided a die for press-forming glass elements, comprising at least a platinum thin film having a thickness of 0.01 to 5 &mgr;m formed on an outermost surface of a press face of a cemented carbide base material.
Those usable as the cemented carbide base material include those containing a major component of tungsten carbide. However, there is no limitation thereto.
As for the thickness of the platinum thin film, a thin layer is sufficiently used provided that the thin film on the die surface is not peeled off due to repeated use. The preferred thickness is determined according to such a viewpoint. The thickness is determined in the same manner for the other aspects of the invention described later on. In the present invention, it is also possible to preferably use the die in which a nickel thin film having a thickness of 0.05 to 0.5 &mgr;m is allowed to intervene between the cemented carbide base material and the platinum thin film.
In a preferred embodiment, it is also possible that an alloy thin film having a thickness of 0.01 to 5 &mgr;m, which contains 10 to 70% by weight of iridium and 30 to 90% by weight of one or more species of metals selected from metals of the platinum group except for iridium, is allowed to intervene between the cemented carbide base material and the platinum thin film. In this embodiment, it is more preferable that the species of metal of the platinum group except for iridium is only platinum.
The die constructed as described above makes it possible to perform the press-forming operation in which the die release performance is excellent without any adhesion or deposition of softened glass material onto the die, even in the case of the use of any one of various glass materials selected depending on the use or application of the glass element, including, for example, crystalline glass materials (non-crystalline materials), chemically tempered glass materials (materials before the ion exchange treatment), and borosilicate glass. Further, V-shaped grooves are formed on the glass substrate as the material for the glass element, and an optical fiber is arranged in the grooves by using an adhesive. Therefore, the adhesive performance is excellent for the optical fiber to be glued to the glass substrate.
It is preferable that the glass element subjected to the press-forming has a surface roughness (Rmax) within a range of 0.4 to 1.2 &mgr;m.
In the present invention, the glass element for optical IC, which belongs to the glass element, is not necessarily subjected to precision machining into one having an extremely small degree of surface roughness. Especially, for example, when the predetermined grooves for embedding the optical fiber are provided by means of the press-forming on a connector part for optically coupling the optical fiber and the IC chip, it is sufficient to give a processing accuracy in such a degree that the optical fiber can be positioned at a submicron level.
An allowable value in view of the positioning accuracy for the optical fiber (single mode), i.e., an upper limit value of the surface roughness of the glass element is preferably not more than 1.2 &mgr;m as represented by Rmax, more desirably not more than 1.0 &mgr;m. On the other hand, from a viewpoint to improve the adhesive performance for the glass fiber to be glued to the glass substrate, it is preferable to increase the adhesion area by providing a certain degree of surface roughness. A lower limit value of the surface roughness of the glass element is preferably not less than 0.4 &mgr;m as represented by Rmax, more desirably not less than 0.5 &mgr;m.
The range of the surface roughness is especially preferred when the glass surface is metallized to fix and secure the optical fiber by means of soldering. The surface roughness of the glass element is herein used as an evaluation standard. However, the surface roughne
Fukuyama Masashi
Hasegawa Hitoshi
Ota Takashi
Tohyama Kazutoshi
Burr & Brown
NGK Insulators Ltd.
Vincent Sean
LandOfFree
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