JPH06168483A - Mold for molding, molding method, polishing device for stamper, polishing method for stamper, stamper and optical information recording medium - Google Patents

Abstract

PURPOSE:To improve the flow of a resin and to prevent the generation of strains and dislocation by changing the space in the mold for molding according to radii. CONSTITUTION:While the conventional stampers are plane, this stamper 1 has the thickness changing according to the radii. For example, the signal surface of the stamper 1 is stuck to a plate 8 meeting the shape of the stamper 1 desired to be obtd. by a polishing stage for the rear surface of the stamper 1 and is polished, by which the thickness in the diametral direction of the stamper 1 is freely controlled. Namely, the thickness is increased in the outer peripheral part of the range A in the radial direction of the stamper 1 in order to balance the flow of the resin and the thickness is made flat in order to improve the signals in the range B. The thickness is increased in order to decrease the strains of the resin in the range C. The thickness in this range is conversely decreased by the packing quantity of the resin, etc., in some cases. The flow of the resin is thereby improved and the generation of sink marks, strains and dislocation is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium (a substrate for a high-density information recording carrier, particularly a plastic substrate) such as a video disc and an optical disc, and a mold for injection molding of the plastic substrate. The present invention also relates to a molding method and a polishing device and a polishing method for polishing the back surface of the stamper for the optical information recording medium into a flat shape (a perfect flat surface without minute irregularities).

[0002]

2. Description of the Related Art Normally, a stamper for recording signals used for injection molding or injection compression molding (hereinafter referred to as molding) of an optical information recording medium is a stamper having a uniform thickness in the radial direction. .

A conventional stamper will be described below with reference to the drawings.

FIG. 6 is a sectional view showing a conventional example of a molding die. As shown in FIG. 6, the stamper 11 has a metal core 2
It is fixed by the holder 3 and is held by the stamper holder 4. A mold cavity 15 is provided facing the metal core 2 so as to be openable and closable. The mold cavity 15 is provided with a cavity side injection port 6 for injecting resin. The holder 3 is provided with a punching pin 7 for punching the center spool. This conventional stamper 11 has a thickness of about 0.3 m, as shown in FIG.
Most of them have a thickness of m or about 0.6 mm, and there is almost no difference in thickness between the inner and outer peripheral directions and the radial direction (0 to 1 μm). In addition, there is also one that is thicker on the inner peripheral side and thinner on the outer peripheral side (Japanese Patent Publication No.
21256).

The molding is performed using such a stamper 11 and the signal is transferred to the optical information recording medium (optical disk) as follows. As shown in FIG. 6, the stamper 11 is fixed to the metal core 2 by the holder 3 with the pattern portion 9 facing upward, and is held by the stamper holder 4 and closed by the cavity 15. However, in order to release the resin gas generated during molding, a clearance is provided at the outer peripheral portion of the cavity to allow the gas to escape. Then, the melted resin is injected from the cavity side injection port 6. The injected resin causes the stamper 11 to move to the metal core 2 with the pressure at the time of injection.
While pressing down, it flows from the inner circumference to the outer circumference.
The gas generated at this time escapes from the gap between the stamper 11 and the stamper holder 4 and the mold cavity 15. When the resin is injected up to the outer periphery, the resin is cured and the signal is transferred by cooling the resin as it is or in a state where the metal core 2 is moved and pressure is applied. Next, the metal 2 is removed from the mold cavity 15, the center spool is punched with the punching pin 7, a center hole is punched, and the disc to which the signal is transferred is removed from the stamper. Next, an optical disc is finished by forming a recording film layer on the signal surface of the molded product by sputtering or the like.

By the way, if the back surface of the optical disk stamper, which is the substrate of the optical disk, is not flat and has a slight unevenness, a problem arises in that the processed data surface cannot follow the light for strain data detection. Therefore, it is necessary to polish the back surface of the optical disk suntaper into a flat boundary surface. Conventionally, a method of polishing such a flat work while rotating the substrate only with a tape-like polishing material (Japanese Patent Laid-Open No. Hei.
For example, there is a so-called lapping machine (see Japanese Patent Application Laid-Open No. 58-59764) for sandwiching and polishing a work between rotary disks that rotate with each other through a liquid abrasive.

[0007]

The above-mentioned conventional method for forming an optical disk has the following problems. First, because the resin flow is non-uniform, the characteristics of the molded product of the optical disk (distortion, fault, smear, stain, transferability of pattern, etc.) are deteriorated. In addition, the wall thickness of the molded product becomes non-uniform, and residual strain remains and the molded product warps or twists. Those that are thicker on the inner peripheral side and thinner on the outer peripheral side have been considerably improved, but further improvement is desired.

Further, according to the conventional polishing method, the polishing surface of the flat plate-shaped work cannot be polished into a perfect flat surface without any fine irregularities. For example, in the case of a lapping method using a lapping machine, the surface roughness can be processed with sufficient accuracy, but the flatness is lost. With tape-shaped abrasives, it is possible to control the thickness variation in the radial direction, but in order to improve the surface roughness accuracy,
Becomes unsuitable.

An object of the present invention is to provide an optical information recording medium having good characteristics as a molded product and having a uniform thickness.

Another object of the present invention is to provide a molding die and a molding method capable of obtaining an optical information recording medium having excellent characteristics as a molded product and having a uniform thickness.

Another object of the present invention is to provide a stamper capable of obtaining an optical information recording medium having excellent characteristics as a molded product and having a uniform thickness, a polishing apparatus and a polishing method therefor.

[0012]

The molding die of the present invention comprises:
In a molding die for molding an optical information recording medium using a stamper in which an information signal or a groove is formed by the shape of unevenness on the surface, the distance between the stamper and the die member on the surface facing the stamper is the stamper. The distance varying according to the radius of and the distance varying according to the radius is obtained by selecting two or more from A to E below. A. B. It has a part which becomes narrower continuously according to the radius. C. There is a portion having a different amount of change in the content of “having a portion that becomes narrower continuously according to the radius”. D. It has a continuously widened portion depending on the radius D. E. There is a portion having a different amount of change in the content of "having a portion that continuously increases depending on the radius". In this case, there is a portion where the distance does not change even if the radius changes. In this case, even if the distance between the stamper and the die member on the surface facing the stamper changes due to the change in the plate thickness of the stamper, And the distance between the stamper facing surface and the mold member may vary depending on the curved surface of the stamper facing surface of the mold member.

The stamper polishing apparatus of the present invention is a polishing apparatus for polishing a stamper for an optical information recording medium as a flat plate-like work with a tape-like polishing cloth and an abrasive, and rotating the flat plate-like work. Rotation mechanism,
It is characterized by comprising a moving mechanism for moving the tape-shaped polishing cloth relative to the flat work, a transfer mechanism for transferring the tape-shaped polishing cloth, and a supply mechanism for supplying the abrasive.

[0014]

According to the molding die of the present invention, the adhesion between the stamper and the resin, the shape and presence / absence of the stamper surface uneven pattern, the distance from the resin injection port, the distance from the mold cavity (outer periphery) The stamper plate thickness in the radial direction or the molding part space is changed according to molding conditions (injection pressure, amount, temperature, speed, etc.). This makes the resin flow uniform and improves the characteristics of the optical disk as a molded product.

The polishing apparatus of the present invention can be made by a tape polishing method and by dropping a tape cloth and a polishing agent on the work instead of the tape polishing agent.

[0016]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a graph showing the plate thickness of a stamper used in one embodiment of the molding die of the present invention and the stamper plate thickness of a conventional example.

As shown in FIG. 1, this stamper has a thickness that changes depending on the radius. To make such a stamper, in the back surface polishing process of the stamper,
As shown in FIG. 2, there is a method of freely controlling the radial plate thickness of the stamper 1 by bonding the signal surface of the stamper 1 to the plate 8 corresponding to the shape of the stamper to be obtained with an adhesive and polishing.

Stamper 1 produced by this method
An example of the molding conditions will be described. In FIG. 1, in the radial range A, it is preferable that the plate thickness be thick in order to balance the flow of the resin with the outer peripheral portion, and in the range B, the plate thickness is preferably flat to improve the signal. However, in some cases, it may be possible to obtain a better molded product by slightly increasing the mold temperature condition and giving a certain degree of inclination as in other examples described later. In addition, the radial inclination of the stamper plate thickness, which is the best condition, greatly changes depending on the size of the molded product. Range C
Then, thicken the resin to reduce distortion. Of course, there may be a case where the outer peripheral portion is thinned conversely depending on the filling amount of the resin.

By controlling the stamper plate thickness according to the molding conditions, the stamper conditions (surface condition, pattern shape), the size of the molded product, the required accuracy of the molded product, etc., the space inside the mold can be controlled and better. It is possible to obtain various molded products.

In this embodiment, the space inside the mold was controlled only by controlling the stamper plate thickness.
As shown in FIG. 3, the same result can be obtained by using the stamper 11 having a uniform thickness and the mold cavity 5 having a curved surface. 3, the same symbols as those in FIG. 6 indicate the same elements.

In addition, a stamper, a mold cavity,
Better results are obtained by using the present invention for single or multiple components such as mold cores.

Next, an embodiment of the polishing apparatus of the present invention will be described.

As shown in FIG. 4, this polishing apparatus polishes a stamper 101 for an optical disc, which is a flat work piece, with a tape-shaped polishing cloth 107. This polishing apparatus includes a rotary table 103 that is a rotating mechanism that rotates the stamper 101, a moving mechanism (not shown) that reciprocates the polishing cloth 107 between the roll 104 and the winding roller 106, and the polishing cloth 107 on the stamper 101. Pressing roller 105 for pressing and abrasive 110
And a nozzle 109 for supplying the gas, and the rotary table 103 rotates the stamper 101. The polishing agent 110 is supplied to the rotating polishing surface of the stamper 101 while moving the tape-shaped polishing cloth 107 in the direction of the arrow in the figure. In addition, the moving mechanism causes the polishing cloth 107 to reciprocate in the radial direction of the workpiece for polishing.

That is, in this embodiment, since the polishing cloth 107 and the polishing agent 110 are used for polishing, good surface roughness can be obtained. Further, since the polishing cloth 107 is in contact with the stamper 101 which is the work only by its width, only the necessary portion (radius) can be polished, and the polishing amount of the work in the radial direction can be freely controlled.

The roll 104 has a polishing cloth 107 (SURFIN018 manufactured by Fujimi Abrasives Co., Ltd.) with a width of 40 mm.
It is in the form of a roll. The polishing cloth 107 wound around the roll 104 is taken up by the take-up roller 106.
Between the stamper 101 and the stamper 101.
It has a rotating mechanism (not shown) for continuously supplying it with a mechanism for pressing it to 1. The used polishing cloth 107 is wound around the winding roller 106. Abrasive 110
(Plastic plastic 700 manufactured by Fujimi Abrasives Co., Ltd.) is nozzle 10
It is dripped from 9 onto the stamper 101. At the same time, the stamper 101 and the glass master 102 are turned tables 103.
To rotate.

Further, the polishing cloth portion (roll 104, pressing 105, winding roller 106) has a moving mechanism for reciprocating in the radial direction of the φ220 mm stamper, and the moving speed can be set for each radial position. Therefore, the polishing amount at each radius can be controlled.

In the stamper 101 described above, a concave-convex resist pattern is formed on the glass master 102, and then a Ni layer of 0.3 to 0.6 mm is formed by Ni electroforming or the like, and the surface of the electroformed layer is processed (stamper). Back surface processing) and master glass 1
The inner and outer diameters of the Ni stamper peeled off from 02 are processed to complete the stamper. The stamper is used as a mold to mass-produce plastic substrates.

Table 1 shows a comparison between the processing according to this embodiment and the conventional examples (lap polishing, tape polishing).

[0030]

[Table 1] As can be seen from Table 1, this example is a processing method that combines the good points of lapping and tape polishing.

As shown in FIG. 5, the pressure roller 1 of FIG.
The same result can be obtained by using the adhesive roller 108 to which the polishing cloth 107 is adhered, instead of 05, and the device structure is simplified.

[0032]

As described above, according to the present invention, by changing the space in the molding die in accordance with the radius, it is possible to prevent the occurrence of sink marks, strains, and faults due to the good flow of resin, and to make the stamper pattern shape. It becomes possible to control the transcription property of.

Further, according to the present invention, since the flat plate-like work which is rotated by the tape-like cloth and the abrasive is polished as described above, the work can be finished as a boundary surface and can be made into a flat surface. In addition, it is possible to polish only the necessary radial position by moving the workpiece in the radial direction. That is, it is possible to freely control the thickness of the work in the radial direction.

Therefore, the characteristics as a molded product are good,
It is possible to obtain an optical information recording medium having a uniform thickness.

[Brief description of drawings]

FIG. 1 is a graph showing a plate thickness of a stamper used in an example of a molding die of the present invention and a stamper plate thickness of a conventional example.

FIG. 2 is a stamper processing reference diagram of an example of a molding die.

FIG. 3 is a sectional view showing another embodiment of the molding die of the present invention.

FIG. 4 is a diagram showing an embodiment of a polishing apparatus of the present invention.

FIG. 5 is a diagram showing another embodiment of the polishing apparatus of the present invention.

FIG. 6 is a cross-sectional view showing a conventional example of a molding die.

[Explanation of symbols]

 1,11 Stamper 2 Metal core 3 Holder 4 Stamper retainer 5 Mold cavity 6 Injection port 7 Stamping pin 8 Plate 9 Pattern part 101 Stamper 102 Glass master 103 Rotating table 104 Roll 105 Pressing roller 106 Take-up roller 107 Polishing cloth 108 Adhesion Roller 109 Nozzle 110 Abrasive

Claims (9)

[Claims] 1. A molding die for molding an optical information recording medium using a stamper having an information signal or a groove formed on the surface by an uneven shape, comprising: the stamper and a die member facing the stamper. The distance A changes according to the radius of the stamper, and the distance changes according to the radius A to E below.
A molding die characterized by being obtained by selecting two or more from A. It has a portion that becomes narrower continuously according to the radius. B. There is a portion having a different amount of change according to the content of “having a portion which becomes narrower continuously according to the radius”. C. It has a part which becomes wider continuously according to the radius. D. There is a portion having a different amount of change in the content of “having a portion that continuously increases in accordance with the radius”. E. It has a portion where the distance does not change even if the radius changes. 2. The molding die according to claim 1, wherein a distance between the stamper and a die member on a surface facing the stamper changes according to a change in plate thickness of the stamper. Mold for molding. 3. The molding die according to claim 1, wherein the distance between the stamper and the die member on the surface facing the stamper changes depending on the curved surface of the die member on the surface facing the stamper. Characteristic molding die. 4. A molding method for molding an optical information recording medium using the molding die according to claim 1. 5. An optical information recording medium obtained by the molding method according to claim 4. 6. A polishing device for polishing a stamper for an optical information recording medium as a flat work with a tape-shaped polishing cloth and an abrasive, comprising a rotating mechanism for rotating the flat work, and the tape-like work. A stamper polishing apparatus comprising: a moving mechanism that moves a polishing cloth relative to the flat work, a transfer mechanism that transfers the tape-shaped polishing cloth, and a supply mechanism that supplies the abrasive. 7. A stamper polishing method using the stamper polishing apparatus according to claim 6. 8. A stamper polished by the stamper polishing method according to claim 7. 9. An optical information recording medium manufactured by using the stamper according to claim 8.