JPH07171902A - Method and apparatus for producing disk substrate - Google Patents

Abstract

PURPOSE:To provide a substrate of high capacity without generating strain in an attached stamper. CONSTITUTION:A mold 1 to which a stamper 4 is attached is filled with a disk substrate material to produce a disk substrate. The stamper 4 is attached by fixing the inner peripheral part of the stamper and fixing the outer peripheral part thereof after the stamper 4 and/or the mold reaches predetermined temp.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a disk substrate such as an optical disk and a disk substrate manufacturing apparatus.

[0002]

2. Description of the Related Art A substrate of an optical disk for reproducing information or for recording / reproducing information using a light beam is generally manufactured by a method such as resin injection molding, compression molding or injection compression molding. At this time, since a concavo-convex pattern called a groove or a pit that the light beam spot follows is formed on the surface of the substrate, a metal plate called a stamper for replicating the concavo-convex pattern is attached on the mirror surface plate of the substrate molding die.

As a method of mounting this stamper, conventionally, a method is known in which an inner peripheral portion is pressed by a claw-shaped holder and an outer peripheral portion is pressed by a ring-shaped holder. However, in the method of fixing with such a holder, it takes a lot of time to install and remove, and downtime becomes long when the stamper is replaced during the production operation. Furthermore, there is a high possibility that the stamper will be damaged during the installation and removal work.

Therefore, a method has been proposed in which the inner peripheral portion and the outer peripheral portion of the stamper are attached to the mirror surface plate by the operation of turning the suction device on and off. According to this, as compared with the claw-shaped holder type, the stamper can be easily attached and detached, the time and effort for exchanging the stamper can be reduced, and the stamper can be quickly operated.

[0005]

By the way, in the above-mentioned proposal in which the inner peripheral portion and the outer peripheral portion of the stamper are fixed by vacuum suction, the vacuum suction line is commonly used for both the inner peripheral portion and the outer peripheral portion of the stamper. At the time of mounting, the stamper is sucked and fixed to both the inner peripheral portion and the outer peripheral portion at the same time.

By the way, when the stamper is attached in a state where the temperature of the mold is low, and then the temperature is raised, the stamper is fixed to the mirror surface plate by the vacuum suction force, but the coefficient of thermal expansion between the stamper and the mirror surface plate. The stamper may be distorted due to the difference. On the contrary, even when the stamper is attached in a state where the temperature of the mold is high, the stamper expands and distorts due to heat conduction.

Then, the distortion of the stamper is transferred to the molded substrate to deteriorate the shapes of the grooves and pits, the circularity, and the eccentricity, and the reproduction failure of information such as tracking error of the optical pickup and the recording / reproduction failure are caused. Cause. Therefore,
An object of the present invention is to provide a high-performance substrate in which distortion is not generated in the attached stamper.

[0008]

The above object of the present invention is a method of manufacturing a disk substrate by filling a disk substrate material into a die to which the stamper is mounted, wherein the mounting of the stamper is performed by the stamper. The inner peripheral portion of the stamper is fixed, and after the stamper and / or the mold reaches a predetermined temperature, the outer peripheral portion of the stamper is fixed.

Incidentally, in this disc substrate manufacturing method,
To attach the stamper, fix the inner peripheral part of the stamper, raise the temperature of the mold and after the stamper and / or the mold reaches a predetermined temperature, fix the outer peripheral part of the stamper, It is conceivable to fix the inner peripheral portion of the stamper to the die that has been heated to 1, and fix the outer peripheral portion of the stamper after the stamper reaches a predetermined temperature.

Further, it is particularly preferable that the outer peripheral portion of the stamper is fixed after the expansion due to the thermal expansion of the stamper becomes substantially zero. A vacuum suction method is preferable as the method of fixing the stamper. Further, the object of the present invention is an apparatus for manufacturing a disc substrate by filling a disc substrate material into a die having a stamper attached, and having an attaching means for attaching the stamper to the die. , The mounting means is configured so that the inner peripheral portion and the outer peripheral portion of the stamper can be independently mounted, and
The present invention is achieved by a disk substrate manufacturing apparatus characterized by being configured by a vacuum suction method.

As the disk substrate manufacturing apparatus, various types such as an injection molding apparatus, a compression molding apparatus, and an injection compression molding apparatus can be considered, and the mirror surface plate which is the stamper mounting surface is the core side, the cavity side, Alternatively, a mold of either the movable side or the fixed side may be used. Also, regarding the positions of the inner peripheral portion and the outer peripheral portion where the stamper is adsorbed, even if the shape of the mirror plate side such as a slit groove for vacuum adsorption is deformed to the stamper, the stamper uneven pattern on the stamper is not affected. The positions are preferably inside and outside the signal area.

According to the present invention configured as described above, since the stamper is attached so as not to cause distortion, a high-performance disk substrate is molded and information signals are recorded. -It has excellent reproduction characteristics. Hereinafter, the present invention will be specifically described with reference to examples.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of an essential part showing an embodiment of a disk substrate manufacturing apparatus according to the present invention. In the figure, 1 is a mold for injection molding of an optical disk substrate. In addition, this mold 1
Is divided into a stamper mounting side (optical disk signal surface side) 2 and a stamper facing side (optical disk reading surface side) 3.

No. 4 has a thickness of 250 μm and a groove interval of 1.
It is a stamper made of nickel having a depth of 6 μm and a groove depth of 100 nm. The stamper 4 is fixed to a mirror surface plate (in this embodiment, a mirror surface plate having a TiN coat on the surface of the Star-Bax material) 5 with an inner vacuum suction slit groove 6 and an outer vacuum suction slit groove 7. To be done. The inner vacuum suction slit groove 6 is connected to the vacuum line 6a, and the outer vacuum suction slit groove 7 is connected to the vacuum line 7a. These vacuum lines 6a and 7a are independent of each other. Has become. That is, the vacuum line 6a is connected only to the inner peripheral vacuum suction slit groove 6. The vacuum line 7a is connected only to the outer peripheral vacuum suction slit groove 7. The on / off mechanism for the vacuum line 6a and the vacuum line 7a is also different.

The resin forming the disk substrate is injected through the sprue bush 8 and polycarbonate is filled in the cavity formed by the stamper 4, the mirror surface plate 9 facing the stamper, and the outer peripheral ring 10 that determines the outer diameter, Punch 11 is used to open a center hole, thickness 1.2 mm, inner diameter 15
A polycarbonate optical disk substrate 12 having a diameter of 130 mm and an outer diameter of 130 mm is injection-molded at a mold temperature of 120 ° C.

The temperature of the mold 1 can be controlled by a water temperature type temperature control line 13. By the way, at the time of injection molding of the optical disk substrate 12, the stamper 4 was attached by the following six methods. (1) A vacuum line 6 is provided between the inner peripheral portion and the outer peripheral portion of the stamper 4.
vacuum suction by a and 7a at the same time.
Raise the temperature to 20 ° C. (2) With the mold 1 heated to 120 ° C., the inner peripheral portion and the outer peripheral portion of the stamper 4 are vacuum-sucked simultaneously by the vacuum lines 6a and 7a. (3) The inner peripheral portion of the stamper 4 is vacuum-sucked by the vacuum line 6a, and the outer peripheral portion of the stamper 4 is vacuum-sucked by the vacuum line 7a 15 minutes after the mold 1 is heated to 120 ° C. (4) Stamper 4 with mold 1 heated to 120 ° C
The inner peripheral portion of is vacuum-sucked by the vacuum line 6a, and
After a minute, the outer peripheral portion of the stamper 4 is vacuum-sucked by the vacuum line 7a. (5) The outer peripheral portion of the stamper 4 is vacuum-sucked by the vacuum line 7a, and 15 minutes after the mold is heated to 120 ° C., the inner peripheral portion of the stamper 4 is vacuum-sucked by the vacuum line 6a. (6) With the mold 1 heated to 120 ° C., the stamper 4
The outer peripheral portion of the is vacuum-sucked by the vacuum line 7a,
After a minute, the inner peripheral portion of the stamper 4 is vacuum-sucked by the vacuum line 6a.

Then, the roundness of the groove of the optical disk substrate 12 injection-molded by the disk substrate manufacturing apparatus having the stamper fixed by the above-described six methods was examined. The roundness was evaluated by the maximum value of the radial amplitude of the optical pickup when the optical pickup followed the groove. As a result, [inside the signal area of each optical disk substrate (radius 30
2 shows the measurement results of the circularity of the position (mm position), the inner side (position with a radius of 45 mm), and the outside (position with a radius of 57 mm)].

According to this method, the method according to (3) and (4) is adopted in which the inner peripheral portion of the stamper is fixed, and after the stamper and the mold have reached a predetermined temperature, the outer peripheral portion of the stamper is fixed. It can be seen that the disk substrate having high circularity and little distortion can be obtained. On the other hand, in the case where the method according to (1) and (2) in which the inner peripheral portion and the outer peripheral portion of the stamper are fixed at the same time, only a disk substrate having low roundness and large distortion can be obtained. .

Although the inner peripheral portion and the outer peripheral portion of the stamper are not fixed at the same time, the outer peripheral portion of the stamper is fixed first, and then the inner peripheral portion is fixed (5) and (6). However, the disk substrate with a low circularity and a large distortion is also obtained.

[0020]

[Effect] According to the present invention, a disk substrate having a high roundness, a low distortion, and a high performance can be obtained, and an information signal can be recorded and recorded.
The reproduction characteristics are excellent.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part showing an embodiment of a disk substrate manufacturing apparatus.

FIG. 2 is a graph showing groove circularity of a disc substrate.

[Explanation of symbols]

 1 Mold 4 Stamper 5 Mirror Plate 6 Inner Circumferential Vacuum Suction Slit Groove 6a Vacuum Line 7 Outer Circumferential Vacuum Suction Slit Groove 7a Vacuum Line 8 Sprue Bush 12 Disk Substrate

Claims (6)

[Claims] 1. A method of manufacturing a disc substrate by filling a disc substrate material into a die to which the stamper is attached, wherein the attaching of the stamper is performed by fixing an inner peripheral portion of the stamper and / or Alternatively, after the die reaches a predetermined temperature, the outer peripheral portion of the stamper is fixed, which is a method of manufacturing a disc substrate. 2. The inner peripheral portion of the stamper is fixed, the temperature of the die is raised, and after the temperature of the stamper and / or the die reaches a predetermined temperature, the outer peripheral portion of the stamper is fixed. The method of manufacturing a disk substrate according to claim 1, wherein 3. An inner peripheral portion of the stamper is fixed to a die heated to a predetermined temperature, and after the stamper reaches a predetermined temperature, the outer peripheral portion of the stamper is fixed. The method of manufacturing a disk substrate according to claim 1, wherein 4. The method of manufacturing a disk substrate according to claim 1, wherein the outer peripheral portion of the stamper is fixed after the expansion due to thermal expansion of the stamper becomes substantially zero. 5. The method according to claim 1, wherein the stamper is fixed by vacuum suction. 6. An apparatus for manufacturing a disc substrate by filling a disc substrate material into a die to which the stamper is attached, comprising an attaching means for attaching the stamper to the die. The disk substrate manufacturing apparatus is characterized in that the inner peripheral portion and the outer peripheral portion of the stamper can be independently mounted and configured by a vacuum suction method.