JPS6022080B2 - Mold manufacturing method for high-density recording replica disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for manufacturing a Precadisk from a recording disk in which information is recorded on a metal film by laser processing.

As a recording method capable of ultra-high density recording, there is a method in which a glass disk is coated with a metal film and a portion of this metal film is selectively removed by laser processing to record information.

This will be explained in FIG. Figure 1A is a partial cross-sectional view of the recording disk, Figure 1B' is an enlarged view of a part of the surface of the metal film of the recording disk, and Figure 1C is a partial cross-sectional view of the recording disk. FIG. 3 is an enlarged view of a partial cross section. 1 is a glass disk as a base; 2 is a metal film for a recording medium on which information is recorded; 3 is a processed hole (hereinafter referred to as a bit) in which a signal is recorded by a laser beam; 4 is the recording surface which is the surface of the metal film 2, 1 is the metal film 2 and the glass disk 1 without a bit.
11 is a metal film 2 on which bits are recorded.
This is a record disc consisting of a glass disc and a glass disc.

Next, recording on the unrecorded disc 10 will be explained.

The intensity of the laser beam is modulated in an appropriate manner according to the recording signal, and the laser beam is focused and irradiated onto the metal film 2 of the rotating unrecorded disc 10. When the laser beam is focused and hits the metal film 2, that part of the metal film 2 is instantaneously heated and evaporated or melted and scattered, thereby carving the bit 3. Although this varies depending on the modulation method, information can be recorded based on the shape of the bits 3 in the longitudinal direction or the positional relationship such as the interval. On the recording surface 4 of the metal film 2 recorded in this way, bits are engraved as shown in FIG. 1B, and a cross section along the line x-Y is as shown in FIG. 1C. . Figure 1C
In this case, the third part of the bit has a concave shape because the metal has been removed by evaporation or melting and scattering. A necessary condition for realizing replica records with good characteristics and low cost is that replica records can be produced in large quantities from the record disc 11 recorded in this manner by a process with little deterioration of characteristics. This is a major problem with the spread and development of this type of record. Next, the record board 11
The method for manufacturing the mold necessary for making a replica record will now be explained with reference to FIG.

2A to 2E are partially enlarged cross-sectional views, and the inner peripheral portion of the recording disk 11 is not shown.

The recorder 11 shown in FIG. 2A is the recorder 11 in the same process as FIG. 1C.

FIG. 2B shows a record disk 11 after the surface has been roughened by roughening the metal film 2 on the inner and outer peripheries of the record disk 11, FIG. Figure 2D
Figure 2 shows a recording disk 11 in which the surface of the silver mirror film is plated with nickel after a silver mirror has been applied, and a mold consisting of an integral silver mirror film and a nickel layer is peeled off from the recording disk 11 after plating. A recording disc 11 is produced by rotating an unrecorded disc 10, which has a metal film 2 adhered to a glass disc 1, at a constant speed, and focusing a laser beam whose intensity is modulated according to the recording signal on the metal film 2. .

Then, in the unrecorded portions of the inner and outer circumferences of this record disc 11 shown in FIG. 2A, a predetermined width (for example, about 3 skins)
The metal film 2 is roughened over a period of time. This portion is shown as a surface roughening portion 21 in FIG. 2B. This can be formed, for example, by rotating the recording disk 11 and rubbing it with sandpaper. This is the deckle layer 23 which will be described later.
This is done to prevent the disc from peeling off from the recording disc 11. The record disc 11 subjected to this surface roughening is shown in FIG. 2B. In bit 3 of the metal film 2 of the recording disk 11 in FIG. 2B, the metal has disappeared due to evaporation or dissolution and scattering during recording. Therefore, the glass disk 1 is exposed in the bit 3, and there is no electrode on the plated part necessary for plating.

This becomes a problem in nickel plating, which will be described later.
For this purpose, a silver mirror is formed on the surface of the metal film 2 over the entire surface of the recording disk 11. To explain the silver mirror method, first, a tin chloride solution is applied to the entire surface of the recording disk 11 in order to facilitate the adhesion of the silver mirror film, and then an ammoniacal silver nitrate solution and a glucose solution, which is a reducing agent, are simultaneously applied to record. A silver mirror film is formed on the surface of the disc 11. The recording disk 11 on which this silver mirror was applied is shown in FIG. 2C. 22 is a silver mirror film.

The thickness of this silver nada film is, for example, 1000A to 2000A. Using this silver mirror film 22 as an electrode, nickel is plated. This plating is performed to obtain sufficient mechanical strength for the silver mirror film 22, and the record disc 11 after this plating is shown in FIG. 2D. The thickness of this plating layer is, for example, 0.1 mm. 23 is a nickel plating layer.

In this plating operation, the nickel plating layer 23 does not peel off from the recording disk 11 during plating due to the effect of surface roughening performed over a predetermined width on the inner and outer peripheries of the recording disk 11 described above. As a result, from the recording disk 11 shown in FIG. 2A having a concave bit, the recording surface of the convex bit 3 with little characteristic deterioration is changed from the mirror film 22 and the nickel plating layer 2.
3, and the nickel layer 23 provides sufficient strength. A mold 30 having a convex bit 3 is produced by peeling off the integrated mold made of the silver mirror film 22 and the nickel layer 23 from the recording disk 11. This mold 30 is shown in FIG. 2E. Now, in the process of making the mold described above, the silver mirror film 22 can be easily formed and is effective as an electrode when nickel plating the recording disk 11 with the bit 3, but on the other hand, since the silver particles are large, The surface properties are inferior to that of metal film 2, the silver is soft and the bits are deformed when peeled off, resulting in slightly poor transfer fidelity, care must be taken in handling, and the metal film is made of chemically resistant materials such as aluminum. The bad ones also had drawbacks such as corrosion of the metal film during the silver mirror process and deterioration of characteristics.

This invention was made to eliminate the above-mentioned drawbacks.Instead of the process of applying a silver mirror on the recording disk, a process of attaching a metal protective film was introduced, which made it strong and robust, and made it possible to improve the strength of the nickel. It has excellent chemical resistance in the plating process, and the surface graininess is better than that of the mirror surface, making it easier to perform the subsequent nickel plating process and providing a method for manufacturing high-quality molds. be.

An embodiment of the present invention will be described below with reference to FIG.

Figure 3A shows a recording disk with bits formed by laser processing using the method described above, Figure 3B shows a state in which a metal protective film has been attached, and Figure 3C shows a state in which nickel plating has been further applied. Figure D is a diagram showing a mold formed by peeling off the nickel plating layer. FIG. 3A shows a recording disk 11 having a metal film 2 on which bits 3 are formed on a glass disk 1 by the method described above.

Next, as shown in FIG. 1B, a metal protective film 31 is formed by vapor deposition on the recording disk 11, and the unevenness of the surface becomes a new signal transfer surface. Next, the metal protective film 31 and the metal film 2 (1)
When nickel metal is used as an electrode (10) and nickel plating is applied, a nickel plating layer 23 as shown in FIG. A mold 50 made by this method is obtained by peeling off only the nickel plating layer as shown in FIG. In contrast to the mold 30 described in FIG. 2, which is an integrated type of silver mirror film and nickel plating layer, the mold of the present invention consists only of the nickel plating layer 23, as shown in FIG. 3. . The material of the metal film 2 may be a material with strong chemical resistance, such as a chromium thin film or a chromium-gold-monochromium laminated film, or a material that is weak against plating solutions, such as aluminum, for reasons described later.

The film thickness is, for example, several 100A to 2000A. The difference from the method described above lies in the step of attaching a metal protective film instead of the coin mirror, which will be described in more detail.

In FIG. 3B', metal is attached to the metal protective film 31 by vapor deposition, etc., and the material is easy to vapor deposit onto the recording disk 11, has strong adhesion to the substrate 1 and the metal film 2, and retains the original bit shape. A suitable material is one that retains the original properties faithfully, has strength and chemical resistance that can withstand cleaning prior to nickel plating, and has good surface granularity.

Chromium, titanium, gold, and silver had good adhesion to the substrate, and nickel had particularly excellent surface properties. The thickness of the metal protective film 31 may be sufficient as long as the exposed portion of the glass base of the bit 3 can also be used as an electrode when nickel plating is applied. According to experiments, the nickel plating on the bit part progressed well with metal thickness 2, which was about half that of a kite with a thickness of about 0.1 mm, and the fidelity of the bit was also good. In addition, when the metal film 2 is made of aluminum or the like with poor chemical resistance, it is particularly effective compared to a silver mirror, and can withstand the nickel plating process with few pinholes and vapor deposition. In this case, it is effective to increase the thickness of the metal protective film 31 from about twice the thickness of the metal film 2, to lessen the corrosion of the metal film, and to prevent information from being lost. When a mold is made using the method of this invention and a replica disk is made, the surface quality of the disk is better than that with silver mirror treatment, and the noise generated from the surface is suppressed by 15 to 2
We were able to reduce it compared to the previous year. In addition, in the state shown in Figure 3B, both the pet part and the non-bit part are light-reflecting surfaces, and optical reproduction can be performed using the principle of interference similar to that of a replica disk at the final stage. Since it is possible to evaluate the record disc before it goes through the process, the yield of pre-recorder production has improved significantly.

In addition, although vapor deposition was explained as a manufacturing method of a metal protective film during description, it goes without saying that sputtering method may also be used.

Also, although the surface roughening step was omitted in the description of this invention, the necessity is the same as in the above-mentioned method.

As described above, according to the present invention, by incorporating a process of attaching a metal protective film to the recording disc 11 instead of applying a silver mirror, it has excellent chemical resistance in the nickel plating process and strength resistance in the peeling process. , it is possible to transfer bits with better fidelity, the transfer surface has better graininess than a silver mirror, and it is possible to make a good mold.

A mold made from this mold through a plurality of nickel plating processes and a replica disk transferred from the mold have the advantage of having higher bit fidelity and better surface quality.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a recording disk related to the mold manufacturing method according to the prior art, Fig. 2 is a process diagram showing the mold manufacturing process, and Fig. 3 is a process diagram showing an embodiment of the mold manufacturing method of the present invention. It is a diagram. In the figure, 1 is a glass substrate, 2 is a metal film, 3 is a bit, 4 is a recording surface, 10 is an unrecorded disc, 11 is a recording disc, 12 is a surface roughening part, 22 is a silver mirror film, 23 is a nickel plating layer, 30 is a mold, 31 is a metal protective film, and 50 is a mold. In the figures, the same reference numerals indicate the same or equivalent parts. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A step of forming pits corresponding to information by laser light on a metal film formed on one main surface of a substrate, and a metal protection layer thicker than the thickness of the metal film on which the pits are formed. A method for manufacturing a mold for a high-density recording replica disk, comprising the steps of attaching a film, forming a nickel plating layer on the metal protective film, and peeling off the nickel plating layer. 2. A mold manufacturing method for a high-density recording replica disk according to claim 1, wherein the metal protective film is formed of a chromium film. 3. The method for manufacturing a mold for a high-density recording replica disk according to claim 1, wherein the metal protective film is formed of a nickel film. 4. The method for manufacturing a mold for a high-density recording replica disk according to claim 1, wherein the metal protective film is formed of a titanium film. 5. The method for manufacturing a mold for a high-density recording replica disk according to claim 1, wherein the metal protective film is formed of a thin gold film. 6. The method for manufacturing a mold for a high-density recording replica disk according to claim 1, wherein the metal protective film is formed of a thin silver film.