JPH0447902B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to information recording disks such as video disks and compact disks, and a method for manufacturing the same, and particularly to information recording disks and methods for manufacturing the same, which can be mass-produced by a method of creating a large number of replicas from a stamper. It relates to its manufacturing method.

BACKGROUND ART Discs manufactured by copying replicas using stampers For example, in the case of optical video discs, replicas are produced by transferring irregularities corresponding to recorded signals on the stamper surface using transparent resin by injection, compression, ZP, etc. It was necessary to prepare the material and then perform metallization by vapor deposition or sputtering. Metal thin films formed by such metallization are indispensable in the case of optical disks because they are used as reflective films for laser beams for signal reading, but both the vapor deposition and sputtering processes must be performed under vacuum, which reduces productivity. This has been difficult to increase, and has been an obstacle in efforts to reduce disk manufacturing costs.

FIG. 1 shows the case of a compact disk (or digital audio disk) as an example of such a disk manufacturing process. As shown in the figure, a replica 2 is created by injection molding a resin such as PMMA using a stamper 1 made of a metal such as nickel and made from a predetermined original plate. Next, this replica 2
A metal reflective film layer is formed by a vapor deposition process on the surface of the stamper 1 onto which the unevenness of the surface has been transferred, resulting in state 3. Furthermore, in the next step, a protective film is applied on the metal reflective film layer to form a disk 4 having a smooth surface.

FIG. 2 similarly shows the manufacturing process of a conventional optical video disc, and the steps up to the application of a protective film are the same as those for compact discs. In the case of an optical video disc, in order to make a disc that can be played on both sides, two discs 4 with a protective film created in the above process are bonded together using a predetermined adhesive layer with the protective film on the inside. By this,
A disk 5 having signal recording layers on two surfaces, the front and the back, is formed.

Compact disks and optical video disks are manufactured in large quantities through the manufacturing process described above, but as mentioned above, vapor deposition or sputtering is required to generate the metal reflective layer, so processing equipment is required. The drawback is that it is difficult to improve productivity because it is complicated and requires precise control. Therefore, it has been desired to develop an information recording disk and its manufacturing process that can perform all manufacturing processes in the atmosphere.

SUMMARY OF THE INVENTION The present invention improves the drawbacks of the prior art as described above, and
It is an object of the present invention to provide an information recording disk capable of directly transferring a surface shape from a stamper to a metal thin film layer, and a disk manufacturing method using this method.

The information recording disk according to the present invention is characterized in that a superplastic alloy is used as the metal thin film layer,
The manufacturing method is characterized by including the steps of placing a metal foil made of such a superplastic alloy on a predetermined substrate, heating it to a desired temperature and pressing it against a stamper to transfer the surface shape.

Examples Examples of the information recording disk and the method for manufacturing the same according to the present invention will be described below with reference to the drawings. Before entering into the description of the examples, first, an outline of the superplastic alloy used in the present invention will be explained.

Superplasticity is a phenomenon in which certain metals can be deformed under low stress under specific temperature conditions, and has been known for a relatively long time. Possible causes of superplasticity include grain boundary slip in materials with fine crystal structures (on the order of μm) and changes in crystal behavior above and below the transformation point of materials, including allotropic transformation. With the development of chemical technology, a wide range of plastic superplastic alloys have been discovered, regardless of whether they are non-ferrous alloys or ferrous alloys. The temperature at which superplasticity is exhibited varies depending on the composition of each alloy; for example, in the case of Zn-22Al alloy, it is 200 to 300
The value is in °C.

When such superplastic alloys are applied to optical disks, Al-based, Mg-based, Cr-based, and Ni-based alloys, which have particularly high reflectance among various superplastic alloys, are used as the optical beam reflecting film of the disk. Alloys such as are suitable. As an example, in the case of Al -4.2Ca -4.5Zn alloy, the elongation rate is 400 at a tensile rate of 2 mm/m at 500℃.
% value is obtained.

FIG. 3 is a diagram showing the principle of the method for manufacturing an information recording disk according to the present invention in comparison with the prior art, and is particularly an example when applied to a compact disk. In the figure, a reflective metal foil 12 made of a superplastic alloy is pressed against a metal stamper 11 made by a conventional method to transfer its surface shape. Next, the reflective metal foil is peeled off from the stamper 11,
A sub-plate made of a light-transmitting material is adhered to the transfer surface side of the reflective metal foil 13 onto which the recorded signals have been transferred, thereby obtaining a disk 14 from which signals can be read.

FIG. 4 is a diagram showing the principle of the method for manufacturing an optical video disc according to the present invention, and the steps up to the step of bonding sub-plates to obtain the disc 14 are the same as those shown in FIG. Optical video discs are usually manufactured as discs that can be played on both sides, so two discs 14 with sub-plates attached are provided, and the video disc 1 is created by pasting them together with the sub-plates facing outward.
Get 5.

As described above, the present invention is very advantageous in terms of reducing manufacturing costs because all disk manufacturing processes are performed in the atmosphere without using time-consuming processes such as vapor deposition and sputtering. In addition, because the structure is almost the same as that of conventional disks in which the signal recording surface is covered with a sub-plate, it has the characteristics of conventional optical disks, such as easy handling and less signal deterioration due to scratches. I have it all.

Next, this disk manufacturing process will be further explained with reference to a specific example shown in FIG.

First, in step P1, a metal foil 20 having a thickness of 50 to 100 microns and made of a superplastic metal alloy whose main component is a metal with high reflectivity such as Al, Mg, Ni, or Cr is laminated onto a predetermined substrate 21. This substrate 21 is made of a heat-resistant material and will be separated from the metal foil in a later process, but is required for the purpose of preventing deformation and damage when the metal foil 20 is peeled off from the stamper 22. still,
In the figure, the adhesive layer between the metal foil 20 and the substrate 21 is omitted. Next, in step P2, a disk consisting of the metal foil 20 and the substrate 21 is made, for example.
The metal foil 20 is heated to a temperature between 200° C. and 600° C. at which the metal foil 20 exhibits appropriate plasticity. On the other hand, Ni is made from a predetermined original plate and has unevenness on its surface according to the recording signal.
A stamper 22 consisting of the like is prepared and heated to preferably the same temperature as the metal foil 20 in step P3. If the temperature difference between the stamper 22 and the metal foil 20 is large, the temperature of the metal foil 20 will change during transfer, which is not preferable. Next, in step P4, the stamper 22 is attached to the metal foil 2 by pressing or rolling.
0 to transfer the surface shape of the stamper 22 onto the surface of the metal foil 20. Next, in step P5, the metal foil 20 is peeled off from the stamper 22 together with the substrate 21. In step P6, a predetermined sub-plate 23 (or sub-plate) is adhered to the surface of the metal foil 20 peeled off from the stamper using an ultraviolet curing resin (UV resin). Here, 24 indicates an adhesive layer. Next, in step P7, the substrate 21 is moved from the metal foil 20 with the sub-plate 23 adhered to the surface.
Separate. In the case of a compact disk, the disk obtained in this way in step P7 is used as the final disk, as described above.
For optical video discs, further process P8
In this step, the two disks are bonded together using a predetermined adhesive layer 25 with the metal foil 20 side facing inside. The manufacturing of an optical video disc capable of double-sided playback is carried out in the manner described above, except for steps P1 to P4 up to thermal transfer to the stamper 22 and step P6 of separating the substrate 21, which is almost the same as the conventional method. It is clear that each step is performed according to the method.

The reference photo is a micrograph (magnification approximately x 2000) showing the state of the metal foil surface after shape transfer from the stamper obtained by the above manufacturing method. This is an example when an alloy containing .5% is used. As is clear from this figure, a series of pits similar to those of conventional disks are formed on the surface of the metal foil, and it can be understood that it can be used as an information recording disk in the same way as conventional disks. .

As described above, the information recording disk according to the present invention has the excellent feature that the manufacturing process can be simplified and all processes can be performed in the atmosphere, making it easy to reduce costs. Although the above embodiments are examples in which superplastic alloys are used as metal reflective films for compact discs, optical video discs, etc., the invention is not limited to this, and various methods such as methods of reading signals by changing capacitance can be used. It is clear that the present invention can be used for a disk of the type mentioned above and its manufacturing process. In that case, it goes without saying that various plastic alloys may be used as the superplastic alloy, in addition to those whose main component is a metal with a high reflectance as shown in the above embodiments.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the manufacturing process of a conventional compact disc, FIG. 2 is a diagram schematically showing the manufacturing process of a conventional optical video disc, and FIG. 3 is a diagram schematically showing the manufacturing process of a conventional compact disc. Similarly, FIG. 4 is a diagram schematically showing the manufacturing process of the optical video disc according to the present invention, and FIG. 5 is a diagram schematically showing the manufacturing process of the optical video disc according to the present invention. FIG. Explanation of symbols of main parts, 20...Metal foil, 22
... Stamper, 23 ... Substrate, 24 and 25 ... Adhesive layer.

Claims (1)

[Scope of Claims] 1. An information recording disk characterized in that it is made of a superplastic alloy and includes a metal layer on its surface having a shape corresponding to recorded information. 2 The superplastic alloy is a superplastic alloy whose main component is any one of aluminum, magnesium, chromium, and nickel, which are metals with high reflectance, and the metal layer made of the superplastic alloy is coated in a predetermined manner. 2. The information recording disk according to claim 1, wherein the information recording disk is used as a reflector for a light beam. 3. A method for manufacturing an information recording disk having a metal layer made of a superplastic alloy, comprising the steps of placing a metal sheet made of a predetermined superplastic alloy on a predetermined substrate, and the metal sheet placed on the substrate. A step of heating the metal sheet to a temperature exhibiting desired plasticity and pressing it onto a stamper having a surface shape corresponding to the recorded information to transfer the surface shape, and covering the transfer surface of the metal sheet with a predetermined coating layer. A method for manufacturing an information recording disk, comprising the steps of: separating the substrate from the metal sheet coated with the transfer surface.