JPH08111038A - Production of rolled stamper for molding optical information recording medium - Google Patents

Abstract

PURPOSE: To obviate the occurrence of crack by deviating a focus from a just focus or/and deviating the irradiation central position of a laser beam from the butt part of a different material when a flexible stamper and fixtures consist of mutually different materials. CONSTITUTION: This process for producing rolled stamper 5 for molding optical information recording media comprises forming a thermoplastic synthetic sheet which is a substrate material by an extrusion method and forming rugged signals on the sheet by a pair of rolls for molding at the time of forming a ruggedness on the substrate of optical information recording medium which is recorded and reproduced by using light beams. At this time, the fixtures 4 are welded to both ends of the flexible stamper 3 having the ruggedness formed and further, grooves having nearly the same shape as the shape of the fixture 4 are formed on the rolls. The fixtures 4 are inserted into these grooves and one of the fixture is provided with a mechanism for applying tension. The flexible stamper 3 and the fixtures 4 are then welded with a laser by deviating the focus from the just focus to form weld beams 2. Next, the flexible stamper 3 is fixed to a roller with the fixture 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a roll-shaped stamper for molding an optical information recording medium, and more specifically, a roller groove for manufacturing a transparent substrate of an optical information recording medium for optically recording / reproducing information. The present invention relates to a method for manufacturing a roll stamper used in a molding method.

[0002]

2. Description of the Related Art Conventionally, magnetic materials such as magnetic tapes and magnetic disks, and various semiconductor memories have been mainly used for recording various information. Such magnetic memory and semiconductor memory have an advantage that information can be easily written and read, but on the other hand, the contents of information can be easily rewritten and high-density recording cannot be performed. was there.

In order to solve such problems, an optical information recording method using an optical recording medium has been proposed as a means for efficiently handling a wide variety of information, and an optical information recording carrier and a recording / reproducing method therefor have been proposed. A recording / reproducing apparatus has been proposed. The optical recording medium as such an information recording carrier,
In general, laser light is used to volatilize a part of the optical recording layer on the information recording carrier, to cause a change in reflectance, or to cause deformation so that information is obtained by a difference in optical reflectance or transmittance. Recording or playing. In this case, the optical recording layer is a so-called DRAW (direct read after write) medium that can be “read directly after writing” without the need for development processing after writing information, and high density recording Since it is possible and additionally writable, it is effective as an information recording / storing medium.

In a general optical recording medium, a stamper in which an uneven pattern corresponding to a track or information is recorded on a polycarbonate resin or a polymethylmethacrylate resin which is a thermoplastic material of a substrate is used to form the uneven pattern. Transferring to form grooves.

As a method for forming the groove on the information recording medium substrate, an injection molding method or a compression molding method is used. However, the specifications of the information recording medium substrate require that the flatness and smoothness of the substrate be high at the optical level. In the injection molding method or compression molding method, defects such as warpage and inclusion of bubbles are liable to occur, which significantly impedes information detection by light. Therefore, control of temperature and pressure, precision of mold, generation of bubbles It is very difficult to prevent it, and the size of the device itself is large, so that the production cost is high. Further, in the compression molding method, since it is a single-wafer treatment, the post-process is complicated and the productivity is low.

[0006] Since a plastic flat plate can be easily manufactured with a smooth and uniform plate with little air bubbles mixed in, a method has been proposed in which a stamper is brought into close contact with this flat plate to apply pressure to transfer the uneven pattern. Very large pressure was required to apply uniform pressure to the whole.

As a method of solving these problems, a roller for passing the molten resin extruded from the T die of the extruder between the molding roller and the mirror surface roller and transferring the uneven pattern of the molding roller with a small pressure. There is a method of manufacturing an information recording medium substrate by a groove molding method.

The roller / groove molding roll is formed by welding fixing tools to both ends of a flexible stamper having irregularities, and further forming grooves on the roller having substantially the same shape as the fixing tools, and fixing the rollers in the grooves. A roll stamper has been used in which a flexible stamper is fixed to a roller by inserting a tool and providing a mechanism for applying a tension to at least one of the fixing tools.

FIG. 8 is a schematic view showing a conventional stamper with a fixture, FIG. 8 (A) is a plan view thereof, and FIG. 8 (B) is a schematic sectional view taken along the line BB '. In the same figure, the fixing tool 4 is welded to both ends of the flexible stamper 3 having the concavo-convex shape. As a welding method for the flexible stamper 3 and the fixing tool 4, a few mm from the end of the fixing tool 4 is used. The weld bead 2 was formed at the position. Reference numeral 1 is a crack generated in the weld bead due to the setting conditions of the welding device.

[0010]

However, in the above-mentioned conventional example, since the fixing tool and the flexible stamper are made of different materials, cracks are easily generated in the weld bead portion, which is fixed to the roller and used as a roll stamper. It had the following drawbacks.

(1) In the roller / groove molding method, in order to increase the flatness and smoothness of the information recording medium substrate to an optical level, the surface accuracy and heat distribution characteristics of the roll stamper are not good. Don't Surface accuracy,
In addition, in order to improve the heat distribution characteristics, high tension was applied to the fixture to improve the close contact between the flexible stamper and the roller. Therefore, there is a trade-off relationship in which the welded portion is damaged.

(2) When welding a flexible stamper and a fixture under high power conditions, the penetration depth becomes deeper and the weld strength is apparently improved, but cracks occur in the weld bead. Therefore, the welding strength is low. Further, since the welding distortion is large, it causes defective release, and the stamper itself is bent.

The present invention has been made in view of the above-mentioned prior art, and particularly when the flexible stamper and the fixture are made of different materials, the focus is shifted rather than the just focus, and / or the laser is used. By shifting the irradiation center position of the beam from the abutting part of different materials, the penetration depth of the welding bead and the composition ratio of the welding bead (alloy composition in which different metals are fused to form an alloy) are changed, An object of the present invention is to provide a method for manufacturing a roll-shaped stamper capable of molding a substrate for an optical information recording medium having high flatness without generating cracks.

[0014]

That is, according to the present invention, a thermoplastic resin sheet, which is a material of a substrate of an optical information recording medium for recording and reproducing by using light, is extruded by an extrusion method, and is extruded by a pair of molding rolls. A roll-shaped stamper used to form an uneven signal on a sheet, a fixture is welded to both ends of a flexible stamper in which unevenness is formed, and a roller is provided with a groove having substantially the same shape as the fixture,
In a method of manufacturing a roll-shaped stamper in which a fixing tool is inserted into the groove and a mechanism for applying a tension is provided on at least one of the fixing tools, and the flexible stamper is fixed to a roller, the flexible stamper and the fixing tool are just-focused. A method for manufacturing a roll-shaped stamper for molding an optical information recording medium, characterized by shifting the focus or / and displacing the irradiation center position of the laser beam from the abutting portion of the flexible stamper and the fixture, and welding with a laser. Is.

The present invention will be described in detail below. The method for manufacturing a roll-shaped stamper for molding an optical information recording medium of the present invention is a thermoplastic synthetic sheet which is a substrate material by an extrusion method in a step of manufacturing unevenness on a substrate of an optical information recording medium for recording and reproducing using light. In the step of forming an uneven signal on the sheet with a pair of molding rolls, a fixing tool is welded to both ends of a flexible stamper having unevenness, and a groove having substantially the same shape as the fixing tool is further provided on the roll. In a method for manufacturing a roll-shaped stamper in which a fixing tool is inserted into this groove and a tension is applied to at least one of the fixing tools, and the flexible stamper is fixed to a roller, the flexible stamper and the fixing tool are provided with a just focus. The focus of the laser beam and / or the flexible center of the laser beam irradiation center And forming a weld bead welded by laser offset from abutting part of over the fixture.

The present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view of a stamper with a fixture obtained by the method for producing a roll-shaped stamper for molding an optical information recording medium of the present invention. FIG. 1 (A) is a schematic view of a stamper with a fixture in which the end of the flexible stamper 3 is abutted against the stepped portion of the fixture 4 and welded with the focus shifted rather than the just focus, and FIG. [Fig. 4] is a partial sectional view taken along the line AA '. In FIG. 1, 3 is a flexible stamper having unevenness corresponding to a fine uneven pattern of a substrate for an information recording medium, 4 is a fixing tool for fixing the flexible stamper to a roller, and 2 is welding the flexible stamper and the fixing tool. It is a weld bead that is formed when

FIG. 2 is an explanatory view showing an example of the welding method according to the present invention. FIG. 2A shows a state in which the flexible stamper 3 and the fixture 4 are welded with just focus (focus amount = 0 mm). On the other hand, in the present invention, as shown in FIG. 2 (B), the flexible stamper 3 and the fixture 4 are shifted by a focus amount a (mm) from the just focus shown in FIG. 2 (A). Weld with.

The value of the focus amount a (mm) is usually 0.
5 to 1.7 mm, preferably 0.8 to 1.5 mm is desirable. If it is less than 0.5 mm, cracks occur in the weld bead portion, so that the welding strength becomes small, and if it exceeds 1.7 mm, the welding portion hardly melts and the welding strength becomes small, which is not preferable.

In FIG. 2, reference numeral 15 is a lens for welding, and 16 is a laser beam irradiated through the lens.

FIG. 3 is an explanatory view showing another example of the welding method according to the present invention. FIG. 3 shows the laser used in FIG.
A method of displacing the irradiation center position of the beam from the abutting portions of the different materials of the flexible stamper 3 and the fixture 4 and welding them will be described. b indicates the amount of displacement from the abutting portion, usually 0.
1 to 0.3 mm, preferably 0.15 to 0.25 mm is desirable. If it is less than 0.1 mm, the alloy composition ratio of the welding bead does not change, so cracks are likely to occur, and 0.3
If it exceeds mm, the welded position of the weld will shift too much.
As a result, the welding strength decreases, which is not preferable.

It is preferable that the flexible stamper and the fixture to be welded are made of different materials, the flexible stamper is a nickel material, and the fixture is a stainless steel material (SUS material). The penetration depth of the welding bead formed in the abutting portion is 0.1 to 0.4 mm, preferably
It is preferably 0.2 to 0.3 mm. 4 and 5 are micrographs (magnification: 150 times) showing the presence or absence of cracks by adjusting the focus amount.

FIG. 6 is a process explanatory view showing a method of manufacturing a flexible stamper by electroforming. In the figure,
6 is a glass substrate such as soda lime glass, 7 is a photoresist for patterning on the glass substrate, and 7a is a fine pattern of irregularities such as tracking grooves and information pits obtained by exposing and developing the photoresist. , 8
Is a glass master obtained by forming a fine pattern of irregularities such as tracking grooves and information pits on the glass substrate, 9 is a conductive film for forming a metal film on the glass master, and 13 is an electroforming method. The metal film 3 formed on the glass master having the conductive film formed thereon is a flexible stamper obtained by simultaneously separating the conductive film and the metal film from the glass master.

As shown in FIGS. 6A to 6E, first, a photoresist 7 is applied to the surface of the glass substrate 6, and a fine pattern 7a of irregularities such as tracking grooves and information pits is formed thereon. By doing so, the glass master 8 is obtained. Next, after the conductive film 9 is formed on the surface of the glass master 8, a metal film 13 is formed by an electroforming method, the surface of the metal film 13 is further polished, and then the conductive film 9 and the metal film 13 are formed. At the same time, the flexible stamper 3 is obtained by peeling from the glass master 8.

FIG. 7 is a schematic sectional view showing an example of an RG (roller grooving) device. In the figure, 1
1 is an extruder for extruding pelletized resin such as polycarbonate (PC) pellets at a constant speed while melting, 10 is a T-die for bringing the molten resin extruded from the extruder closer to the molding shape, and 5 is an extruded from the T-die. Roll-shaped stamper for transferring a fine pattern of irregularities such as tracking grooves and information pits to the melted resin, 12
Is a mirror surface roller for adjusting the plate thickness and the mirror surface of the information recording medium substrate, and 14 is a small roller through which the molten resin extruded from the T die of the extruder is passed between the roll stamper and the mirror surface roller. It is a continuous sheet of an information recording medium substrate obtained by transferring the uneven pattern of a molding roller.

Using the RG apparatus shown in FIG. 7, the molten resin extruded from the extruder 11 is passed through the T-die 10, and further between the mirror-like roller 12 and the roll stamper 5 for transferring the fine pattern of the unevenness. By transferring the concavo-convex pattern of the molding roller with a small pressure throughout, a continuous sheet of the information recording medium substrate can be obtained.

[0026]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

Example 1 First, a flexible stamper was manufactured by an electroforming method based on the process explanatory diagram showing the method of manufacturing the flexible stamper in FIG. First, in the step of FIG. 6A, the photoresist 7 was formed on the glass substrate 6 such as soda lime glass.
The photoresist 7 was dropped on the glass substrate 6 using Az1370 (Hoechst Japan Co., Ltd.).
It was applied to a film thickness of 000Å. After that, 90 ℃, 30mi
Prebaking was performed under the condition of n.

Next, in the step of FIG. 6B, a laser exposure device and a Mirror Projecior Mask Aligner MPA-1500 are used.
An exposure device such as (Canon Inc.) is used to expose a predetermined pattern (striped pattern) of a plurality of information recording media,
By developing with a developer Az312MIF (Hoechst Japan Co.), fine patterns 7a having irregularities such as tracking grooves and information pits were formed, and a glass master 8 for an optical card was manufactured.

Further, in the step of FIG. 6C, as a pretreatment for forming a metal film by an electroforming method, a film forming apparatus such as a sputtering apparatus or a vapor deposition apparatus was used for conducting treatment. The conductive film 9 was formed on the glass master 8 by forming a nickel film having a film thickness of 1000Å to 2000Å by a sputtering device.

Next, in the step of FIG. 6 (D), a metal film 13 was formed on the glass master disk 8 provided with the conductive film 9 by electroforming. Conductive film 9 in nickel sulfamate electroforming solution
While rotating the glass master 8 having been subjected to the step of 20 to 30 rpm, nickel metal having a thickness of 100 to 200 μm is deposited under the condition of a time integrated value of energizing current of 150 to 300 AH (ampere hour) to form a metal film 13. did.

The electroforming liquid used here has the following composition. Nickel sulfamate tetrahydrate _{[Ni (NH 2 SO 3)} 2 · 4H 2 O] 500g / l boric acid _{[H 3 BO 3] 35~38g /} l pit inhibitor 2.5 ml / l

Next, the metal film 13 is polished, and finally, as shown in FIG.
In the step (E), the conductive film 9 and the metal film 13 are integrally separated from the glass master 8 at the same time, the photoresist adhering to the surface is removed, and laser cutting is performed to obtain a line and space: 9.5 μm /
Flexible stamper 3 with 2.5 μm, step: 2500 Å to 3000 Å stripe-shaped guide groove formed
was gotten.

Next, after aligning the end of the flexible stamper with the end of the fixture (material SUS430), Y
AG laser welding machine: JK701 (manufactured by Lumonix)
Were welded under the conditions shown in Table 1.

Conventionally, as shown in FIG. 2 (A), welding was performed by irradiating a laser beam with just focus (focus amount = 0 mm).
As shown in FIGS. 8 (A) and 8 (B), the crack 1 was generated in the weld bead 2. In this embodiment, by adjusting the focus amount a as shown in FIG. 2 (B), the penetration depth of the welding bead is controlled and the occurrence of cracks is eliminated.

FIGS. 4 and 5 are micrographs (magnification: 150 times) of the metal structure showing the presence or absence of cracks in the weld bead by adjusting the focus amount. In FIGS. 4A to 4C and FIGS. 5D to 5F, the focus amount is -1.0.
mm, -0.5 mm, +0.5 mm, +1.0 mm, +
The crack generation state of the welding bead in the case of 1.2 mm and +1.5 mm is shown.

As shown in FIGS. 4 and 5, by shifting the focus amount a to the plus side, the occurrence of cracks can be suppressed. In addition, it can be seen from the micrograph that almost no cracks are generated when the focus amount a is 0.5 mm or more. When the focus amount a is shifted to the plus side, the generation of cracks can be suppressed, but the penetration depth of the welding bead decreases and the welding strength tends to decrease.

As a result of confirming the sectional shape of the weld bead, a penetration depth of 0.2 to 0.3 mm was obtained when the focus amount was +1.2 mm, but there was almost no penetration when the focus amount was +1.5 mm. I understand. From the above results, the focus amount +1.2 mm was an appropriate value, and the focus amount +1.2 mm was set as the standard condition.

In this way, the flexible stamper with a fixture shown in FIGS. 1A and 1B was obtained. The flexible stamper was attached to a roller provided with a groove having substantially the same shape as that of the fixture in advance, and the roll-shaped stamper 5 was manufactured by fixing the roller while applying tension.

Next, using this roll-shaped stamper 5, roller / groove molding was performed by the RG apparatus shown in FIG. The molten resin of polycarbonate is extruded from the T-die 10 of the extruder 11 at a resin temperature of 280 ° C. to 320 ° C., passed through between the roll stamper 5 and the mirror surface roller 12, and a small uneven pattern of the roll stamper 5 is applied with a small pressure. No damage was found in the welded part of the flexible stamper, and it was possible to manufacture the continuous sheet 14 of the substrate for information recording medium on which a good concavo-convex pattern was transferred even after 30 hours.

Example 2 A flexible stamper 3 was produced in the same manner as in Example 1 and welding was performed under the same welding conditions as in Example 1, but only the focus amount a was set to +0.5 mm. Changed to.

As shown by the presence or absence of cracks by adjusting the focus amount in FIGS. 4 and 5, the focus amount a is +
With the setting of 0.5 mm, the weld beads 2 are hardly cracked, but they are not completely crack-free. (This is a limit condition for preventing the occurrence of crack 1) Under the above condition setting, as shown in FIG. 3, the irradiation center position of the laser beam is set to b =
By shifting by 0.2 mm, the composition ratio of the weld beads (fusion of different metals to form an alloy) was changed, and the generation of cracks could be completely eliminated. Further, the penetration depth of the welding bead formed on the butting portion was 0.3 mm.

In this way, the flexible stamper with a fixture shown in FIGS. 1A and 1B was obtained. The flexible stamper was attached to a roller provided with a groove having substantially the same shape as that of the fixture in advance, and the roll-shaped stamper 5 was manufactured by fixing the roller while applying tension.

Next, using this roll-shaped stamper 5,
As a result of attempting roller / groove molding by the RG device shown in FIG. 7, as in Example 1, the welded portion of the flexible stamper was not damaged, and information recording in which a good concavo-convex pattern was transferred even after 30 hours had passed. A continuous sheet of media substrate 14 could be produced.

[0044]

As is apparent from the above description, according to the present invention, when the flexible stamper and the fixture are made of different materials, the focus is shifted rather than the just focus or / and the laser beam is irradiated. By shifting the center position from the abutting part of different materials to change the penetration depth of the welding bead and the composition ratio of the welding bead, no cracks occur and the following remarkable effects are achieved. You can (1) In the roller / groove molding method, in order to improve the surface accuracy and heat distribution characteristics of the roll stamper,
High tension on the fixture does not damage the weld. (2) It is possible to increase the flatness and smoothness of the information recording medium substrate to an optical level, and further, even in continuous molding for 24 hours, a continuous sheet of the information recording medium substrate on which a good uneven pattern is transferred. It became possible to obtain.

[Brief description of drawings]

FIG. 1 is a schematic view of a stamper with a fixture obtained by the method for manufacturing a roll-shaped stamper for molding an optical information recording medium of the present invention.

FIG. 2 is an explanatory diagram showing an example of a welding method according to the present invention.

FIG. 3 is an explanatory diagram showing another example of the welding method according to the present invention.

FIG. 4 is a photomicrograph of a metal structure showing the presence or absence of cracks in a weld bead by adjusting the focus amount (magnification: 150 times).
Is.

FIG. 5 is a photomicrograph of the metal structure showing the presence or absence of cracks in the welding bead by adjusting the focus amount (magnification: 150 times).
Is.

FIG. 6 is a process drawing showing a method for manufacturing a flexible stamper by electroforming.

FIG. 7 is a schematic cross-sectional view showing an example of an RG device.

FIG. 8 is a schematic view showing a conventional stamper with a fixture.

[Explanation of symbols]

 1 crack 2 weld bead 3 flexible stamper 4 fixture 5 roll stamper 6 glass substrate 7 photoresist 7a fine pattern of unevenness 8 glass master 9 conductive film 10 T-die 11 extruder 12 mirror surface roller 13 metal film 14 for information recording media Continuous sheet of substrate 15 Lens 16 Laser beam

Front page continued (72) Inventor Toshiya Yuasa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. A thermoplastic resin sheet, which is a material for a substrate of an optical information recording medium for recording / reproducing by using light, is extruded by an extrusion method, and a pair of molding rolls forms an uneven signal on the sheet. Is a roll-shaped stamper used for, the fixing tool is welded to both ends of the flexible stamper in which the unevenness is formed, the roller is provided with a groove having substantially the same shape as the fixing tool, and the fixing tool is inserted into the groove, and In a method of manufacturing a roll stamper in which a mechanism for applying a tension to at least one of fixing devices is provided and a flexible stamper is fixed to a roller, in the flexible stamper and the fixing device, a focus is shifted more than a just focus or / and a laser is used.・ Laser by shifting the irradiation center position of the beam from the abutting part of the flexible stamper and fixture A method for manufacturing a roll-shaped stamper for molding an optical information recording medium, which comprises welding by means of. 2. The method for manufacturing a roll stamper for molding an optical information recording medium according to claim 1, wherein the materials of the flexible stamper and the fixture are a nickel material and a stainless material, respectively. 3. The method for producing a roll-shaped stamper for molding an optical information recording medium according to claim 1, wherein the penetration depth of the welding bead formed on the butting portion is 0.1 to 0.4 mm.