JPH052784A - Reproducing method for optical disk - Google Patents

Abstract

PURPOSE:To shorten the cycle of stages and to improve productivity by separating the respective stages for reproduction. CONSTITUTION:A radiation curing resin 6 is applied on the surface of a radiation transparent substrate 2 at the time of reproducing the optical disk. This resin 6 is irradiated with radiations 8 and is thereby half cured. A stamper 10 is press welded onto the half cured resin 6 to transfer stamper information. The resin 6 is again irradiated with the radiations 8 and is completely cured after the peeling of the stamper 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reproducing an optical disc on which information such as a video disc, a digital audio disc, a document file disc or the like is recorded.

[0002]

2. Description of the Related Art Conventionally, injection molding, compression molding,
The hot stamp method, cast molding method and the like are known. The injection molding method is a method in which a molten thermoplastic resin is injected and injected under high pressure into a cavity of a mold under high temperature and high pressure to reproduce, and the compression molding method is performed by inserting the thermoplastic resin into the mold. After molding under high temperature and high pressure, it is a method of replicating by cooling the mold and curing the resin, and the hot stamper method is a mold cooled to a film of heated thermoplastic resin. It is a method of pressing and molding. Each of these methods has excellent productivity, but in recent years, densities have been increasing, and very minute irregularities (inverted pits or grooves) on the mold have been achieved.
However, there are disadvantages in that the transfer accuracy is inferior for replicating, and the manufacturing equipment is large-scale and expensive because the process is performed under high temperature and high pressure.

On the other hand, the injection molding method is a so-called injection molding method in which the resin is cured by irradiation with ultraviolet rays or electron beams.
By using a radiation-curable resin, the molding time is shortened and the transfer accuracy is good, so that attention has been paid to it. As a method of duplicating an optical disc using this radiation-curable resin, a stamper having pits or groups formed on the surface thereof and a transparent resin substrate are opposed to each other, and the radiation-curable resin is injected into the gap to form a transparent resin substrate. By irradiating ultraviolet rays from the back side to cure the radiation curable resin and to bond it to the transparent resin substrate, and then peeling between the stamper and the radiation curable resin, pits in which the transparent resin substrate and the stamper are reversed, or There is a method of obtaining a duplicate disk in which the groove-transferred radiation-curing resin is integrated.

[0004]

By the way, in recent years, optical discs on which various types of information are recorded or which can be recorded have a tendency to be produced in small quantities and in a large variety of products. As a production system therefor, production management is easy, Moreover, single-wafer production systems with short lead times are receiving attention. In this production system, it is required that the individual processes be synchronized and have high speed and high reliability. However, the above-mentioned cast molding method using a radiation curable resin having good transferability will reduce productivity in the molding process. There were the following drawbacks. That is, in the conventional cast molding method using a radiation-curable resin, when a liquid radiation-curable resin is injected between the stamper and the transparent substrate or spread thinly by pressurization, it is easy to include air bubbles inside the resin. However, this process must be performed at a low speed in order to prevent the inclusion of air bubbles, and the speed cannot be increased, resulting in poor productivity.

Further, the radiation curable resin is required to have adhesiveness to the transparent substrate and releasability from the stamper at the same time. However, in reality, since the quality of the duplicate disk is important, a material having good adhesiveness is selected. Therefore, the peeling process also needs to be performed over a long period of time, which also results in poor productivity. Further, in the conventional molding method, it is difficult to define the spread due to the flow of the radiation curable resin into a circular shape, and there is a tendency that an excessive radiation curable resin is generated or an uncured portion remains. For this reason, it is necessary to perform operations such as removing the surplus portion by contour shaping by punching and removing the uncured portion by masking exposure, and these operations deteriorate the performance of the duplication disk, resulting in a production yield. There was a problem of lowering it. The present invention has been made to pay attention to the above problems and to solve them effectively. An object of the present invention is to provide a method of duplicating an optical disc, in which each step of duplication is separated to shorten the cycle of the steps, thereby improving productivity.

[0006]

In order to solve the above problems, the present invention provides a first step of applying a radiation curable resin to the surface of a circular radiation transparent substrate, and the applied radiation curable resin. A second step of semi-curing the semi-cured resin by irradiating it with radiation, and a third step of transferring the information by pressing a stamper on which information is previously formed on the surface of the semi-cured radiation curable resin. It is configured to include a step and a fourth step of completely curing the semi-cured radiation-curable resin to which the information is transferred by irradiating the radiation.

[0007]

Since the present invention is configured as described above, a radiation curing resin application step, a stamper information transfer peeling step,
Since each step such as the curing step by irradiation with radiation is completely separated, each step can be shortened, and as a result, productivity can be improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical disk duplicating method according to the present invention will be described in detail below with reference to the accompanying drawings. Figure 1
FIG. 4 is an explanatory diagram for explaining an example of the method of the present invention. As shown in FIG. 1 (a), reference numeral 2 denotes a radiation transparent substrate formed in a circular flat plate shape.
A central hole 4 is formed in the center of the. The radiation transmissive substrate 2 is made of, for example, a transparent resin in order to transmit radiation. Here, the radiation includes not only electromagnetic waves in the range of ultraviolet rays to infrared rays but also electromagnetic waves having a short wavelength such as γ rays and particle beams such as electron beams.

First, on the upper surface of the radiation transparent substrate 2,
The radiation curable resin 6 is applied in a ring shape. The applied portion is only the area to which the pits, grooves, etc., which are information signals, are to be transferred, and an effective means therefor is, for example, a printing method. In this printing method, for example, as a screen used in the case of screen printing, a screen having a high mesh number, a wire having a small diameter, or preferably a metal sheet which has been subjected to surface treatment by etching into an appropriate pattern, It is preferable that the resin surface after printing is flat. This resin surface is made smooth by a heating roller or the like, if necessary. Further, as the radiation curable resin 6, a thin film can be obtained by using a resin having a low viscosity, so that the amount of warpage can be reduced. As a method for obtaining a thin coating film having a smooth surface, a spray method may be used instead. For example, when a radiation-curable resin having a viscosity of 10 to 50 centipoise is spray-coated on the radiation-transparent substrate 2 where only the information area is exposed by masking, unlike the case of screen printing, the radiation-transparent substrate surface comes into contact. Because there is nothing,
There is an advantage that the bonding surface between the radiation curable resin 6 and the radiation transmissive substrate 2 can be cleaned and the bonding can be performed firmly.

Next, as shown in FIG. 1B, radiation is applied from the coating surface 2a of the radiation-curable resin 6 of the radiation transmissive substrate 2, that is, the rear surface of the stamper as viewed from the transfer surface,
For example, ultraviolet rays 8 are irradiated. The ultraviolet rays 8 pass through the radiation transparent substrate 2 and are absorbed by the radiation curable resin 6. At this time, the amount of ultraviolet rays to be irradiated is set so that the radiation curable resin 6 is in a semi-cured state in which the resin 6 still has viscosity. Next, as shown in FIG. 1C, a stamper 10 is pressure-bonded to the upper surface of the radiation-cured resin 6 in the semi-cured state, and pits 12 or grooves formed as information in advance are formed on the stamper 10. Reverse transfer.

Next, the stamper 10 and the radiation transparent substrate 2
Is peeled off on the transfer surface 14, and at this time, maintaining the transferred pit shape on the upper surface of the radiation curable resin 6 is the reason why the radiation curable resin 6 is in the semi-cured state as described above. .. When the pit shape is not sufficiently retained, the ultraviolet ray 8 may be irradiated from the back surface side of the radiation transmissive substrate 2 under pressure. The semi-cured radiation-curable resin 6 that retains the pit or groove shape is shown in FIG.
As shown in (d), it is completely cured by further irradiating with ultraviolet rays 8b from the back side of the radiation transmissive substrate 2,
Thereby, the optical disc 16 is completed. by the way,
When the pits or grooves of the stamper 10 are transferred to the radiation curable resin 6, the stamper 10 and the radiation transparent substrate 2
When pressure-bonding is carried out, bubbles are likely to be contained between these surfaces, so that accurate transfer may not be possible.

FIG. 2 is a diagram for explaining a measure for solving the above problem. As shown, the radiation transparent substrate 2
Is heated, and the heated substrate 2 is placed on the cooled pressing plate 20. Then, the lower surface of the radiation transmissive substrate is cooled, and due to the difference in thermal expansion between the both surfaces, the central portion thereof is curved so as to rise as shown in FIG. By pressing the stamper in this curved state, the pressing contact surface expands from the central portion of the radiation transmissive substrate 2 to the peripheral portion thereof, and accurate transfer can be performed without containing bubbles. The pressing plate 20 is made of, for example, a transparent resin or the like so as to transmit the radiation. In the single-wafer optical disk production system to which the method of the present invention is applied, the circular radiation transmissive substrate 2 made of transparent resin is supplied from the injection molding machine at a high speed. The temperature of the flexible substrate 2 can be as high as 80 to 100 [deg.] C. Therefore, the pressing plate 20 can be formed into a curved shape required for transfer simply by cooling it with water to about room temperature. Therefore, this method can be adopted without using a special heating means.

FIG. 3 is a diagram for explaining a method of separating the stamper and the radiation transparent substrate at high speed. When the stamper 10 that is in contact with the flat surface and the radiation transmissive substrate 2 in which the radiation curable resin 6 is integrated are peeled off at a high speed, a very large peeling force is required. Since the flexible substrate 2 is easily broken, peeling is started from a part of the contact surface between the stamper 10 and the radiation transparent substrate. As shown in FIG. 3, the radiation transparent substrate 2 is supported on a water-cooled pressing plate 20, and the stamper 10 is held on the lower end of a stamper holding block 22. At the center of the stamper holding block 22, the small chamber 2 opened downwards.
4 is provided, and a disc pressing rod 26 is provided in the small chamber 24 so as to be vertically movable. An O-ring 28 is provided as a sliding sealing member between the disc pressing rod 26 and the stamper holding block 22. A gas pressure inlet 30 for supplying pressurized gas to the small chamber 24 is connected to the small chamber 24.

In such a stamper structure, the peeling operation is performed as follows. First, the stamper 10 and the radiation transmissive substrate 2 are pressure-bonded to each other, and then the pressure is stopped.
Is raised together with the stamper holding block 22. At this time,
The disc pressing rod 26 is projected from the stamper holding block 22 to hold down the central portion of the substrate and the gas pressure inlet 3
Pressurized air or pressurized nitrogen gas is supplied into the small chamber 24 through 0 to increase the pressure in the small chamber 24. Then, due to this gas pressure, the radiation transmissive substrate 2 and the stamper 10 are separated from the inner periphery toward the outer periphery, and the radiation transmissive substrate 2 is
It is returned to the holding plate 20. Further, since the O-ring 28 keeps the sealed state in the small chamber 24, the pressure in the small chamber 24 rises when the disc pressing rod 26 descends, and the initial peeling force can be given. As described above, by peeling the stamper and the radiation transparent substrate using the pressurized gas, the peeling operation can be performed quickly without breaking the radiation transparent substrate.

In the embodiment of the present invention, the example in which the radiation-curable resin is provided on only one surface of the radiation-transmissive substrate is shown, but the invention is not limited to this, and the surface hardness may be increased, for example.
It is needless to say that the present invention can be applied to the case where a radiation curable resin is provided on both sides for the purpose of reducing warpage. Also, the radiation curing resin was cured using ultraviolet rays as radiation,
The present invention is not limited to this, and other radiations such as infrared rays and electron beams may be used depending on the properties of the cured resin.

[0016]

As described above, the step of applying the radiation-curable resin, the semi-curing step, the transfer peeling step, and the curing step by irradiation with radiation are completely separated, and the stamper information is transferred in the semi-cured state. The cycle can be shortened and the productivity can be greatly improved. Also,
Since the radiation curable resin is applied by a patterning method such as printing, the step of treating the surplus resin is unnecessary, and therefore the defect occurrence rate can be suppressed. In addition, since a transfer film having a thin and uniform thickness can be obtained, it is possible to supply a duplicate disc having a small change in shape such as warpage.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining a method of copying an optical disc according to the present invention.

FIG. 2 is an explanatory diagram illustrating a method of preventing bubbles from entering between the surfaces when the stamper is pressure-bonded.

FIG. 3 is an explanatory diagram illustrating a method for quickly peeling off a stamper.

[Explanation of symbols]

2 ... Radiation transmissive substrate, 4 ... Center hole, 6 ... Radiation curable resin, 8, 8b ... Ultraviolet ray (radiation), 10 ... Stamper, 1
2 ... Pit (groove), 16 ... Optical disk, 20 ... Cooled pressing plate, 22 ... Stamper holding block, 24
… Small chamber, 26… disc pressure bar, 30… gas pressure inlet.

Claims (1)

Claim: What is claimed is: 1. A first step of applying a radiation curable resin to the surface of a circular radiation transmissive substrate, and a semi-curing process by irradiating the applied radiation curable resin with radiation. A second step of performing, a third step of transferring the information by pressure-bonding a stamper on which information is previously formed on the surface of the semi-cured radiation-curable resin, and a semi-curing on which the information is transferred. And a fourth step of completely curing the radiation-cured resin in a state of being irradiated with radiation.