JPH06259815A - Master for optical disk and its production - Google Patents

Abstract

PURPOSE:To prolong the service life of a stamper and to improve the quality of an optical disk at the time of forming by increasing the hardness of the front signal side or the front signal side and the rear side of the stamper which becomes a master for an optical disk, reducing friction and increasing heat insulation. CONSTITUTION:In a process for producing a master for an optical disk, a nickel plating film 14 contg. 20-30% polytetrafluoroethylene (PTFE) 16 having <=0.1mum particle diameter is formed on the front side of a stamper by electroless plating in 50-70nm thickness. Since the surface hardness of the resulting master for an optical disk is increased and friction is reduced, the service life of the master is prolonged and the releasability of the inner circumference and that of the outer circumference can be made uniform by increased heat insulation to enhance forming efficiency. When the master is used, an optical disk excellent in optical characteristics and having fine appearance can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc master for producing optical discs such as video discs, digital audio discs, still images and document files.

[0002]

2. Description of the Related Art Generally, an optical disc is promising as an information medium due to its extremely high information density, large S / N ratio and little noise, and is commercialized as a video disc for recording and reproducing digital signals. In recent years, research and development has been carried out as an optical disc.

The conventional master for optical disc and the manufacturing method thereof will be described below with reference to the drawings. FIG. 3 shows an outline of a conventional general optical disc. This is because the digital signal is recorded in a pit shape on the resin substrate,
It is reproduced by a semiconductor laser. In FIG. 3, 1 is a disc, 2 is a resin substrate, 3 is a digital signal portion in the form of pits engraved on the resin substrate 2, 4 is a reflective film formed on the surface thereof, and 5 is a reflective film 4. The protective film 6 is a laser beam for reproduction. The resin substrate 2 is generally mass-produced by a molding method such as injection molding or injection / compression molding. The optical disk master is necessary for manufacturing the resin substrate 2 by a molding method and is attached to a molding die. 4A to 4F show a conventional optical disk master and a method for manufacturing the same. In FIG. 4, 7 is a glass substrate, 8 is a resist film, 9 is a recording laser beam, 10 is a recorded signal portion, 11 is a conductive thin film, 12 is an electroformed plating film, and 13 is a stamper which is an optical disk master. .

In order to manufacture the stamper 13 to be the master for optical disc, as shown in FIG. 4, the glass substrate 7 to be the base is first washed in the step (a), and then the resist film 8 is formed thereon by the spin method. The signal portion 10 is formed by forming and exposing the signal with the recording laser beam 9 in the step (b) and developing the signal in the step (c). Next, in step (d), a conductive thin film of nickel or silver is formed to a thickness of 50 to 100 nm by a sputtering method, an electroless plating method, or the like, and then a nickel plating film 1 is formed by electroforming plating in step (e).
2 is formed to have a thickness of 0.2 to 0.4 mm, and is peeled from the glass substrate in step (f) and the resist film is removed by washing or the like, whereby an optical disk master 13 called a stamper can be obtained. The surface of the stamper thus formed is made of nickel or silver formed by a sputtering method or electroless plating.

[0005]

However, in the above-mentioned structure, the surface of the optical disk master is porous or low in hardness due to nickel or silver formed by the sputtering method or the like, and the heat insulating property is poor. For this reason, the surface of the optical disk master has a large friction, and the melted resin during molding is difficult to flow. Therefore, the gas generated from the melted resin during molding is engulfed, and birefringence tends to increase. Further, since the heat insulating property is poor, the temperature difference between the inner peripheral portion and the outer peripheral portion of the optical disk master during molding becomes large, and the releasability between the inner peripheral portion and the outer peripheral portion is different, and a fault is likely to occur on the signal surface side.

In view of the above conventional problems, the present invention not only improves the reliability of an optical disk master and prolongs its life, but also improves the appearance characteristics and optical characteristics of an optical disk substrate during molding. An optical disc master and a method for manufacturing the same are provided.

[0007]

In order to solve the above problems, an optical disk master of the present invention and a method for manufacturing the same are provided by an electroless method in which the surface of a stamper contains polytetrafluoroethylene (PTFE) having a particle size of 0.1 μm or less. Electroless plating is performed with a nickel plating solution to form a 50 to 70 nm nickel plating film containing polytetrafluoroethylene (PTFE) in the surface coating of an optical disk.

[0008]

According to the present invention, since the hardness of the signal surface or the signal surface and the back surface of the stamper can be increased and the heat insulating property can be improved by the above-mentioned constitution, the stamper surface is less likely to be scratched and the releasing property at the time of molding is good. Therefore, it is possible to extend the life of the optical disc master, improve the transfer efficiency, and improve the quality of the optical disc.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an optical disk master and a method of manufacturing the same according to the present invention will be described in detail below with reference to FIGS. 1 (a) to 1 (g) show a method for manufacturing an optical disc master according to an embodiment of the present invention, and FIG. 2 is a cross-sectional surface view of the optical disc master according to one embodiment of the present invention. FIG. 1A shows a glass substrate 7.
The formation of the resist film 8 on the upper side is shown, and FIG. 1B shows the process of exposure recording with the laser beam 9 corresponding to the digital signal. FIG. 1C shows a glass master disk provided with a digital signal section 10 formed by a laser beam 9 in a developing process. FIG. 1D shows a step of forming a nickel (Ni) metal thin film 11 which is a conductive film for performing a plating process on the glass master by a sputtering method. FIG. 1 (e) shows a step of forming a nickel (Ni) plating film 12 on the metal thin film 11 by an electroforming plating method. As shown, the conductive film 11 whose surface is nickel (Ni) and nickel (N) are
i) A stamper 13 composed of a composite layer with the plating film 12 is obtained.

In FIG. 1 (g), polytetrafluoroethylene (PTFE) having a particle diameter of 0.1 μm or less is formed on the metal thin film 11 which is the signal surface of the stamper 13 in a volume ratio of 2;
1 shows an optical disk master in which a nickel (Ni) plating film containing 0 to 30% is formed to a film thickness of 50 to 70 nm. In this case, first, the stamper 13 is made into a cathode in a 30% aqueous solution of sodium hydroxide (NaOH), and the current 3
0A is flown, and electrolytic degreasing cleaning is performed to remove oil and fat on the stamper surface. Next, it is immersed in pure water or an aqueous solution of sulfuric acid (H ₂ SO ₄ ) having a concentration of 3% for neutralization. Next, polytetrafluoroethylene (PTF) with a particle size of 0.1 μm or less
E) in a volume ratio of 20 to 30% and immersed in an electroless nickel (Ni) plating solution heated to 80 to 90 ° C. for 30 seconds while rocking to obtain polytetrafluorethylene (PTFE). A nickel (Ni) film 14 containing 20 to 30% of particles is formed with a film thickness of 50 to 70 nm.

FIG. 2 is a sectional view of an optical disk master 15 having a plating film containing polytetrafluoroethylene particles 16 thus formed. in this case,
In order to uniformly disperse polytetrafluoroethylene (PTFE) in the electroless nickel (Ni) plating solution, the electroless plating solution needs to be sufficiently stirred and circulated. The plating film containing polytetrafluoroethylene (PTFE) thus formed has a hardness of 500 or more in Vickers hardness and a friction coefficient of 0. 0 as compared with a conventional film of only nickel (Ni). Since it is as small as 1 and has excellent wear resistance, it has effects such as a long life as a stamper, improved reliability and stability. Next, the polytetrafluoroethylene (PTFE) of the present invention
When a stamper having a plating film containing the above is formed on a mold of an injection molding machine, an optical disk is molded with a polycarbonate resin, and a conventional optical disk master without the plating film is molded. The comparison is shown in (Table 1).

[0012]

[Table 1]

The stamper containing the polytetrafluoroethylene of the present invention, which has been subjected to the plating treatment, has a quick start-up of molding, an extended stamper life, excellent appearance characteristics and optical characteristics of the molded disk, and good stability. There was found.

[0014]

As described above, according to the present invention, the particle diameter of the stamper signal surface or both the signal surface and the back surface is 0.1 μm.
An optical disk master having a nickel (Ni) film containing polytetrafluorethylene as described below having a film thickness of 50 to 70 nm has a hard stamper surface, excellent heat insulating properties, and a plating film with little change over time is formed. Therefore, the appearance of the disk molded with the stamper formed of the nickel (Ni) film containing the polytetrafluorethylene of the present invention is good, the optical characteristics such as birefringence are excellent, the molding start-up is quick, and the stamper life is also long. It is possible to provide a highly reliable master disk for an optical disk that is long and can improve mass productivity in disk production.

[Brief description of drawings]

FIG. 1 is a sectional view of a step showing an optical disc master and a method for manufacturing the same in an embodiment of the present invention.

FIG. 2 is a surface cross-sectional view of an optical disk master according to an embodiment of the present invention.

FIG. 3 is a sectional view of a general optical disc.

FIG. 4 is a cross-sectional view of steps showing a conventional optical disk master and a method for manufacturing the same.

[Explanation of symbols]

7 Glass Substrate 8 Resist Film 9 Recording Laser Light 10 Signal Part 11 Conductive Film (Metal Thin Film) 12 Electroformed Plating Film 13 Stamper with Surface Metal Thin Film 14 Polytetrafluoretin (PTFE) Particles 2
Nickel plated film containing 0 to 30% 15 Polytetrafluoretin (PTFE) particles 2
Stamper 16 polytetrafluoretin (PTFE) particles provided with a nickel plating film containing 0 to 30%

Claims (3)

[Claims] 1. A signal surface of the stamper or a signal surface and a back surface of the stamper has a particle diameter of 0.
Polytetrafluoroethylene (PTFE) of 1 μm or less
A master for an optical disc provided with a nickel-plated film containing. 2. A surface of a stamper is electrolytically degreased with an alkaline solution, and then a polytetrafluoroethylene having a thickness of 50 to 70 nm is formed by an electroless nickel plating solution containing polytetrafluoroethylene (PTFE) having a particle diameter of 0.1 μm or less. A method of manufacturing an optical disk master comprising forming a plating film containing (PTFE) particles. 3. A plating solution containing at least polytetrafluoroethylene (PTF) having a particle diameter of 0.1 μm or less.
3. The method for producing an optical disk master according to claim 2, wherein the electroless nickel plating solution contains 20 to 30% by volume of E).