JPH05109123A - Method for polishing stamper for optical disk - Google Patents

Abstract

PURPOSE:To produce the stamper for optical disks which has high accuracy as a metallic mold at the time of injection molding and has high durability. CONSTITUTION:This method consists of a polishing stage 1 for moving a polishing tape in the radial direction of the stamper while pressing the polishing tape to the rear surface of the stamper for the rotating optical disk and a rotation and revolution type polishing stage 2 using a mechanochemical polishing material constituted of a polishing material and a chemical etching material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of polishing a stamper for an optical disc.

[0002]

2. Description of the Related Art Optical discs are characterized by their large capacity and high recording density as compared with floppy discs and hard discs, and are currently being actively researched and developed. In general, a substrate for an optical disc is produced by injection molding so that it can be mass-produced while maintaining the above excellent characteristics. At this time, the grooves and pits formed on the stamper are transferred to the optical disc. Therefore, the above stamper is required to have a high degree of precision as a mold and durability in injection molding.

The conventional manufacturing method of the optical disk stamper is performed by the following method, for example. That is, a resist having a required thickness is uniformly applied to a surface-polished glass substrate by a spin coating method, and after prebaking, a desired pattern is exposed by a laser cutting machine, and then the resist is developed to form pits and / or grooves. To do. A thin film of nickel or the like is coated on the surface of the glass substrate with resist having the pits and / or grooves by a sputtering method or the like to maintain conductivity, and then nickel having an arbitrary thickness is extruded by electroforming. Subsequently, nickel is peeled off from the glass substrate and washed. After that, the back surface is polished and washed, and then the inner and outer diameters are processed to complete the stamper.

The stamper is required to have a high degree of precision as a mold and durability in injection molding.
The polishing process on the back side of the stamper becomes important. Up to now, the method has been mainly performed by a rotation-and-revolution polishing method using a mechanochemical polishing agent containing an abrasive and a chemical etching agent as main components. However, with this method, it is difficult to control the polishing amount of the stamper, and there are problems such as the generation of minute protrusions and minute depressions due to slight fluctuations in the amount of polishing agent supplied.

On the other hand, recently, a polishing method has been used in which the polishing tape is pressed against the back surface of a rotating stamper and moved in the radial direction thereof. However, there is a problem that it is difficult to control the warp of the stamper.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to manufacture a stamper for an optical disk which has a high degree of precision as a mold for injection molding and has a high durability. To provide a polishing method.

[0007]

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention by dividing the polishing of the back surface of an optical disk stamper into two steps. Came to do.

That is, the present invention comprises a polishing step 1 in which an abrasive tape is pressed against the back surface of a rotating stamper and moved in the radial direction thereof, followed by an abrasive material and a chemical etching material. The present invention relates to a method for polishing a nickel stamper for an optical disk, which comprises a self-revolving polishing step 2 using a mechanochemical polishing material.

The present invention will be described in detail below.

The type of the polishing tape used in the polishing step 1 does not need to be special, but alumina, diamond, etc. may be used because of its stability as a product and low chemical reactivity. It is desirable to use the main component, and the material and width of the base film are not particularly limited. The winding speed of the polishing tape depends on the size of the polishing agent, but it is 5 to 50 cm.
/ Min is desirable. The rotation speed of the stamper depends on the winding speed of the polishing tape or the moving speed of the stamper in the radial direction, but is preferably 50 to 2000 rpm. Regarding the moving speed of the stamper in the radial direction, depending on the width of the polishing tape, it is 1 to 50 mm /
Seconds are preferred.

Further, it is desirable that the polishing time be arbitrarily set according to the roughness of the back surface of the stamper. If the range of these conditions is not satisfied, the warp of the stamper will increase and the reproducibility of the polishing margin will deteriorate. In addition, a method of discharging a grinding liquid may be used instead of the tape with abrasive grains.

As the polishing agent used in the polishing step 2, it is desirable to use one containing alumina or diamond as a main component for the reasons described above. The dilution rate is 0 to 1
The range of 00% is preferable, and the supply amount is preferably 5 to 100 cc / min depending on the dilution rate. The stamper rotation speed and the pad rotation speed are preferably 5 to 100 rpm, depending on the dilution rate and the supply amount of the polishing agent. Further, the polishing time is arbitrarily set so as to obtain the roughness and thickness required for injection molding. If these conditions are not met, problems such as minute protrusions or minute depressions on the polished surface will occur in addition to the problems described above.

[0013]

EXAMPLES Examples will be given to explain the present invention in more detail, but the present invention is not limited thereto.
Example 1 A signal surface of a stamper obtained by electroforming was protected with a polymer film containing polyvinyl acetate and polyvinyl chloride as main components, and then a fixing hole was opened in the center and fixed to a tape polishing machine. did. Using a tape having a width of 1 inch containing alumina as a main component, the stamper was wound at a speed of 20 cm / min.
Polishing was performed for 5 minutes at a rotating speed of the stamper of 100 rpm and a moving speed of the stamper in the radial direction of 20 mm / sec.

Subsequently, the stamper was removed from the tape polishing machine and attached to a jig of a revolving polishing machine using a double-sided adhesive tape. This stamper was subjected to mechanochemical polishing with an undiluted abrasive containing alumina as a main component at a supply rate of 20 cc / min. This allows
It was possible to obtain a stamper with a small warp, without any minute projections or minute depressions on the polished surface.

[0015]

As is apparent from the above description, according to the present invention, it is possible to manufacture a stamper for an optical disc which has a high degree of accuracy as a mold for injection molding and has a high durability. become.

Claims (1)

[Claims] 1. A method of polishing a back surface of a stamper for an optical disk, which comprises a polishing step 1 in which a polishing tape is pressed against the back surface of a rotating stamper and moved in the radial direction, followed by a polishing material and chemical etching. And a revolving polishing step 2 using a mechanochemical polishing material composed of a material and a polishing material for the optical disk stamper.