JPS6146558B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold manufacturing method for manufacturing a replica disk 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 method will be explained with reference to FIG. Figure 1A is a diagram showing a partial cross section of an unrecorded disc.
FIG. 1B is a partially enlarged view showing a part of the surface of the metal film of the recording disk, and FIG. 1C is an enlarged view showing a partially enlarged cross section of the recording disk. In the figure, 1 is a glass disk as a base, 2 is a metal film attached to the glass disk and used as a recording medium in which information is recorded, and 3 is a processed hole (hereinafter referred to as a pit) 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
0 is a recording disk consisting of a metal film 2 and a glass disk 1 without pits, and 11 is a recording disk consisting of a metal film 2 and a glass disk 1 on which pits are recorded.

Next, recording on the recording board 10 will be explained. The intensity of the laser beam is modulated by an appropriate method according to the recording signal, and the laser beam is focused and applied to the metal film 2 of the rotating recording disk 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 to form pits 3. Various materials can be considered for the metal film, but in our experiments, for example, a thin chromium film formed by vapor deposition or a chromium-gold film was used.
A laminated film of chromium is used, and the film thickness is, for example, several
It is 100 Å to 2000 Å. Although it differs depending on the modulation method, information can be recorded and reproduced depending on the positional relationship such as the longitudinal shape or spacing of the pits 3. On the recording surface 4 of the metal film 2 recorded in this way, pits are carved as shown in FIG. 1B, and a cross section taken along the line XY is shown in FIG. 1C. . In FIG. 1C, the pit 3 has a concave shape because the metal has been removed by evaporation or melting and scattering. A necessary condition for realizing inexpensive replica records with good characteristics 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.

The present invention utilizes the recording disc 11 with good characteristics.
This provides a method for manufacturing molds necessary for making inexpensive replica records.

An embodiment of the present invention will be explained with reference to FIG.
Each figure in Figure 2 is an enlarged view of a partial cross section.
The inner peripheral part of the record disc 11 is not described.
The recorder 11 is shown in FIG. 2A, and the recorder 11 is produced in the same process as in FIG. 1C. Figure 2B is record board 11
Recording disc 11 after surface roughening work in which a number of concentric grooves are carved on metal film 2 over a predetermined width on the inner and outer peripheries of the recorder 11, Fig. 2 C shows a silver mirror applied to the surface of metal film 2 after surface roughening. Recording disc 11, Figure 2D is a recording disc 11 in which nickel was plated on the surface of the silver mirror film after being plated, and Figure 2E is a record disc 11 made of an integrated silver mirror film and nickel layer that has been peeled off from the recording disc 11 after plating. This is the mold 30.

A record disc 1 in which a metal film 2 is coated on a glass disc 1
A recording disc 11 is produced by rotating the disc 0 at a constant speed and focusing a laser beam whose intensity is modulated according to a recording signal on the metal film 2. Then, a predetermined width (for example, about 2 cm) is provided in the unrecorded portions of the inner and outer peripheries of this record disc 11 shown in FIG. 2A.
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 is,
For example, the recording disk 11 may be rotated and rubbed with sandpaper. Further, this is done in order to prevent the nickel layer 23, which will be described later, from peeling off from the recording disk 11. The record disc 11 that has undergone this surface roughening is shown in FIG. 2B. This figure 2B
In the pits 3 of the metal film 2 of the recording disk 11, the metal has disappeared due to evaporation or melting and scattering during recording.

Therefore, the glass plate 1 is exposed in the pit 3, and there is no electrode on the part to be plated which is necessary for plating. This becomes a problem when plating nickel, which will be described later. For this purpose, a silver mirror is applied over the entire surface of the recording disk 11, including the metal film 2. 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 as a reducing agent are simultaneously applied to the recording disk. 11 metal film 2
A silver mirror film 22 is formed on the surface including. The recording disk 11 with this silver mirror is shown in FIG. 2C. The thickness of this silver mirror film 22 is, for example, 1000 Å to 2000 Å. Using this silver mirror film 22 as an electrode, nickel is plated. This plating is performed in order to obtain a mold with sufficient mechanical strength, and the recording disk 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 layer. In this plating work, the above-mentioned record disc 1
The effect of surface roughening performed over a predetermined width on the inner and outer peripheries of the recording disk 1 prevents the plating liquid from penetrating between the metal film 2 and the silver mirror film 22, and the nickel layer 23 is removed from the recording disk 11 during plating. Through the above steps, the recording surface of the convex pits 3 with less deterioration of characteristics from the recording disc 11 of FIG. is formed. By peeling off this integrated structure consisting of the silver mirror film 22 and the nickel layer 23 from the recording disk 11, the convex pits 3
A mold 30 is made. This mold 30 is
Shown in Figure E.

As described above, in the recording disk 11 in which the metal film 2 is deposited on the surface of the glass disk 1 and the pits 3 are recorded by focusing a laser beam whose intensity is modulated according to the recording signal on the metal film 2, Surface roughening is performed on the unrecorded portions of the inner and outer peripheries, and the metal film 2
By applying a silver mirror to the entire surface including the silver mirror, plating the surface of the silver mirror film 22 with nickel, and making the silver mirror film 22 and the nickel layer 23 integral and separated from the recording disk 11, a mold 30 with less deterioration of characteristics can be created. I was able to make it. Replica records can be manufactured in large quantities directly from this mold 30, or from a mold obtained by further plating the mold 30 several times.

As described above, according to the manufacturing method of the present invention, from a disc recorded on a metal film at high density using a laser beam,
It is possible to produce a mold with a high yield with little deterioration of characteristics, and based on this mold, replica records with good characteristics can be manufactured at low cost, which has a great practical effect.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a master disc according to the mold manufacturing method of the present invention, and FIG. 2 is a sectional view of the recording disc and the mold in the process of manufacturing the mold. In the figure, 1 is a glass disc, 2 is a metal film, 3 is a pit, 4 is a recording surface, 10 is a bottom recording disc, 11 is a recording disc, 21 is a surface roughening part, 22 is a silver mirror film, 23 is a nickel layer, 30 is a mold. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. Selectively removing a part of the metal film coated on one principal surface of the substrate to roughen the surface of the metal film over a predetermined width at the inner and outer periphery of the recording disk on which information is recorded. a step of applying a silver mirror film to the entire surface including the metal film of the record disk which has been subjected to the surface roughening; and a step of applying a plating film using the silver mirror film as an electrode on the surface of the record disk on which the silver mirror film has been applied. and, after applying the plating film, peeling off the silver mirror film and the plating film together from the recording disk to form a mold. . 2. The method for manufacturing a mold for a high-density recording replica disk according to claim 1, wherein the plating film is a nickel plating film.