JP2004167979A - Molding die for substrate and stamper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve transcriptability in an outer periphery without heating a mold in a molding die for a substrate up to a high temperature. <P>SOLUTION: A machine comprising a fixed die 1 and a movable die 4 are set at the opposite sites to mold a main surface of a disk substrate by a stamper 10 installed in either of the fixed die 1 or the movable die 4 is structured in such a manner that a heat conduction at the site of the outer periphery of the stamper 10 is poorer than at the site of the center of the stamper 10. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a substrate molding die apparatus and a stamper, and is particularly suitable for application to a substrate molding die apparatus that can ensure good transferability.
[0002]
[Prior art]
In recent years, disk-shaped recording media (hereinafter, referred to as optical disks) in which information signals are written and read using light, such as read-only optical disks, magneto-optical disks, and phase-change optical disks, have become widespread. . The disk substrate used for the optical disk is generally manufactured by an injection molding method. In this injection molding method, a molten resin is injected and injected into a cavity of a substrate molding die apparatus, and the heat of the molten resin is absorbed by a die through a stamper, and the molten resin is cooled and solidified, thereby forming a disk. A substrate is formed.
[0003]
However, in the conventional injection molding method, when manufacturing an optical disk having a large storage capacity, for example, a DVD-R (Digital Versatile Disc-Recordable), the outer peripheral portion of the stamper (for example, a region having a radius of 50 mm or more) is used. There has been a problem that it is difficult to faithfully transfer the shapes of the grooves and pits to the disk substrate. This is because the temperature of the resin forming the outer peripheral portion of the disk substrate is lower than the temperature of the resin forming the central portion, that is, the fluidity of the resin forming the outer peripheral portion of the disk substrate is This is because the fluidity of the resin constituting the central portion is reduced.
[0004]
Therefore, an injection molding method has been proposed in which a disk substrate is molded by holding a mold at a high temperature (for example, 120 ° C. or higher). As described above, by setting the temperature of the mold to a high temperature, the fluidity of the resin is increased, and the shape of the grooves and pits can be faithfully transferred to the disk substrate even at the outer periphery of the stamper.
[0005]
[Problems to be solved by the invention]
However, when the mold is heated to a high temperature in order to secure the transferability of the stamper, there arises a problem that defects of the disk substrate are likely to occur and a problem that the productivity of the disk substrate is reduced. Hereinafter, these problems will be specifically described.
[0006]
1) Unless the mold is sufficiently cooled, the cycle time becomes longer because the disk substrate cannot be removed from the mold.
2) Since the temperature of the disk substrate at the time of removal from the injection molding apparatus is high, the disk substrate is likely to be deformed by the ejector or the removal machine of the injection molding apparatus.
3) Since it is difficult to uniformly release the disk substrate from the mold, defective peeling of the disk substrate is likely to occur.
4) Since the temperature of the disk substrate when taken out of the injection molding apparatus is high, pits and grooves are likely to be deformed when the disk substrate is released from the mold.
5) The disk substrate is easily deformed during cooling.
6) Since the temperature of the mold is high, workability such as stamper replacement is deteriorated.
7) The overall yield decreases.
8) The frequency of occurrence of mold release failures requiring replacement of the stamper increases.
[0007]
Accordingly, an object of the present invention is to provide a substrate molding die apparatus and a stamper that can improve transferability at the outer peripheral portion without raising the temperature of the die.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problem, a first invention of the present application includes a fixed side and a movable side mold that face each other,
In a substrate molding die apparatus configured to mold a main surface of a disk substrate by a stamper disposed on one of a fixed side and a movable side mold,
This is a substrate molding die device, wherein heat conduction on the outer peripheral side of the stamper is deteriorated compared to heat conduction on the center side.
[0009]
The second invention of the present application is directed to a stamper which is arranged on one of a fixed side and a movable side mold provided in a substrate molding die apparatus and is configured to mold a main surface of a disk substrate.
A stamper characterized in that heat conduction on the outer peripheral side is worsened than heat conduction on the center side.
[0010]
According to the present invention, since the substrate molding die device is configured such that the heat conduction on the outer peripheral side of the stamper is worse than the heat conduction on the center side, the temperature of the resin spreading on the outer peripheral portion of the stamper is increased. The drop can be prevented. That is, the fluidity of the resin can be maintained even at the outer peripheral portion of the stamper.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or corresponding portions will be described using the same reference numerals.
[0012]
FIG. 1 is a sectional view showing an example of a substrate molding die apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the substrate molding die apparatus includes a fixed die 1 and a movable die 4.
[0013]
The fixed mold 1 is provided in a state fixed to an injection molding apparatus main body (not shown). The fixed mold 1 is provided with a fixed mirror 1 b so as to face the movable mold 4. The fixed mirror 1b is provided with an arrangement surface 1c on which the stamper 10 is arranged so as to face the movable mold 4. The fixed-side mirror 1b is made of a metal, for example, stainless steel having a thermal conductivity of 25 W / m · k is used as the metal.
[0014]
A sprue bush 2 having a path for the molten resin material is fitted into the fixed mold 1. The sprue bush 2 is provided with a resin injection port 2b. The resin injection port 2b is located at the center of the cavity 3, and injects a synthetic resin material such as a molten polycarbonate resin supplied from an injection molding unit (not shown) into the cavity 3.
[0015]
The movable mold 4 is provided so as to be movable in a direction approaching and separating from the fixed mold 1 (a left-right direction in the drawing). The movable mold 4 is provided with a movable mirror 4 b so as to face the fixed mold 1. The movable side mirror 4b is provided with a molding surface 4c so as to face the stamper 10 forming the molding surface of the fixed side mirror 1b. The movable mirror 4b is made of a metal, for example, stainless steel having a thermal conductivity of 25 W / m · k.
[0016]
In the movable mold 4, a center punch 5 for punching a center hole in the formed disk substrate, and the formed disk substrates located on the inner and outer peripheral sides of the center punch 5, respectively. Protruding members 6a and 6b for removal are provided.
[0017]
The outer peripheral ring 7 is formed in an annular shape, and is slidably mounted in a groove between the movable mirror 4b and an interlock ring 8 provided on the outer peripheral side of the movable mirror 4b. In a state where the fixed mold 1 and the movable mold 4 are in contact with each other, the stamper 10 as the molding surface of the fixed mirror 1b, the molding surface 4c of the movable mirror 4b, and the outer peripheral ring 7 A cavity 3 is formed. Reference numerals 1a, 2a, 4a and 5a denote temperature control circuits formed inside the fixed mirror 1b, the sprue bush 2, the movable mirror 4b and the center punch 5, respectively. In the interlock ring 8, a plurality of gas vent holes 9 are formed in order to release gas generated from the resin material filled in the cavity 3.
[0018]
FIG. 2 is an enlarged sectional view showing an example of the fixed-side mirror 1b in the area 10a shown in FIG. As shown in FIG. 2, the arrangement surface 1c of the fixed mirror 1b has a plurality of recesses 1d in a region in contact with the outer peripheral portion of the stamper 10, for example, in a region in contact with a range of a radius of 54 to 60 mm of the stamper 10. The recess 1d is for reducing the contact area between the surface of the stamper 10 opposite to the disk substrate forming surface (hereinafter referred to as the back surface) and the arrangement surface 1c of the fixed-side mirror 1b. It has a hemispherical shape of 0.1 mm or less. The concave portion 1d formed on the arrangement surface 1c is formed by cutting, electric discharge machining, etching, or laser machining.
[0019]
FIG. 3 is a plan view showing an example of the arrangement surface 1c in the region 10a shown in FIG. As shown in FIG. 3, the plurality of recesses 1d are arranged concentrically around the sprue bush 2.
[0020]
According to the first embodiment of the present invention, the following effects can be obtained.
The substrate molding apparatus includes a fixed mold 1 and a movable mold 4 that face each other. The stationary mold 1 is provided with an arrangement surface 1c for disposing the stamper 10 on the side facing the movable mold 4. A plurality of recesses 1d are provided in a region of the arrangement surface 1c in contact with the outer peripheral portion of the stamper 10 to reduce the contact area. Thus, the fixed mold 1 can be configured such that the heat conduction on the outer peripheral side of the stamper 10 is worse than the heat conduction on the center side. Therefore, it is possible to prevent the temperature of the resin constituting the outer peripheral portion of the disk substrate from lowering and to maintain the fluidity of the resin. Therefore, the transferability at the outer peripheral portion can be improved without raising the temperature of the substrate molding die apparatus.
[0021]
Further, since the transferability of the stamper 10 can be improved without increasing the temperature of the substrate molding die device (for example, to 120 ° C. or higher) as in the related art, the disk substrate can be moved from the substrate molding die device. It is possible to shorten the time required for cooling the substrate molding die device when taking out. Therefore, the cycle time can be reduced.
[0022]
Further, it is possible to prevent pits and grooves from being deformed when the disk substrate is released from the substrate molding die apparatus. Further, since it is easy to uniformly release the disk substrate from the substrate molding die apparatus, it is possible to reduce the rate of occurrence of defective peeling of the disk substrate. Further, the rate of occurrence of defects due to deformation of the disk substrate during cooling can be reduced. Further, the rate of occurrence of defects of the stamper can be reduced. Further, the overall yield can be improved.
[0023]
Next, a second embodiment of the present invention will be described. FIG. 4 is an enlarged sectional view of a fixed mold provided in a substrate molding mold apparatus according to a second embodiment of the present invention. As shown in FIG. 4, the fixed side mirror 1b includes a heat insulating layer 1e near the outer peripheral portion of the stamper 10, for example, at a portion corresponding to a range of a radius of 54 to 60 mm of the stamper 10. The heat insulating layer 1e is formed in an annular shape around the sprue bush 2, for example. The heat insulating layer 1e is, for example, an air heat insulating layer having a heat conductivity of 0.03 W / mk. According to the second embodiment of the present invention, the same effects as in the first embodiment can be obtained.
[0024]
Next, a third embodiment of the present invention will be described. On the arrangement surface 1c of the fixed-side mirror 1b according to the third embodiment, a thin film is provided in a region in contact with the outer peripheral portion of the stamper 10, for example, in a region in contact with a range of a radius of 54 to 60 mm of the stamper 10. This thin film has, for example, an annular shape and is formed by applying a material having a lower thermal conductivity than the material forming the fixed-side mirror portion 1b to the arrangement surface 1c by thermal spraying or the like. As a material applied to the arrangement surface 1c, for example, zirconia having a thermal conductivity of 1.2 W / mk is used. According to the third embodiment of the present invention, the same effects as in the first embodiment can be obtained.
[0025]
Next, a fourth embodiment of the present invention will be described. In the above-described first embodiment, an example in which a plurality of recesses are provided on the arrangement surface 1c of the fixed-side mirror 1b has been described. In the fourth embodiment, however, a plurality of recesses are provided on the outer peripheral portion of the back surface of the stamper 10. A recess is provided. According to the fourth embodiment of the present invention, the same effects as in the first embodiment can be obtained.
[0026]
Next, a fifth embodiment of the present invention will be described. In the above-described third embodiment, an example is shown in which the arrangement surface 1c of the fixed-side mirror 1b is provided with a thin film made of a material having a lower thermal conductivity than the material forming the fixed-side mirror portion 1b. In the fifth embodiment of the present invention, a thin film made of a material having a lower thermal conductivity than the material forming the fixed-side mirror 1b is formed on the outer peripheral portion of the back surface of the stamper 10. According to the fifth embodiment of the present invention, the same effects as in the first embodiment can be obtained.
[0027]
As described above, the embodiments of the present invention have been specifically described. However, the present invention is not limited to the above embodiments, and various modifications based on the technical idea of the present invention are possible.
[0028]
For example, the numerical values given in the above embodiment are merely examples, and different numerical values may be used as needed.
[0029]
Further, at least two of the first, second, third, fourth, and fifth embodiments described above may be combined.
[0030]
FIG. 5 shows an example in which the above-described first embodiment and second embodiment are combined. As shown in FIG. 4, by forming the concave portion 1 d and the heat insulating layer 1 e on the fixed mirror 1 b, it is possible to further prevent the temperature of the resin spreading on the outer peripheral portion of the stamper 10 from decreasing.
[0031]
【The invention's effect】
As described above, according to the present invention, the mold apparatus for forming a substrate is configured such that the heat conduction on the outer peripheral side of the stamper is worse than the heat conduction on the center side. The fluidity of the resin spreading on the outer peripheral portion of the stamper can be maintained without raising the temperature of the mold. That is, the transferability at the outer peripheral portion can be improved without raising the temperature of the mold as in the related art.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of a substrate molding die device according to a first embodiment of the present invention.
FIG. 2 is a sectional view of a fixed-side mirror according to the first embodiment of the present invention.
FIG. 3 is a plan view of a fixed-side mirror according to the first embodiment of the present invention.
FIG. 4 is a sectional view of a stationary mold according to a second embodiment of the present invention.
FIG. 5 is a sectional view of a fixed mold for explaining a modification in which the first and second embodiments of the present invention are combined.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fixed side die, 1a, 2a, 4a, 5a ... Temperature control circuit, 1b ... Fixed side mirror, 1c ... Arrangement surface, 1d ... Depression, 1e ... Heat insulation layer , 2 ... sprue bush, 3 ... cavity, 4 ... movable side mold, 4b ... movable side mirror, 4c ... molding surface, 5 ... center punch, 6a, 6b ...・ Projecting member, 7 ・ ・ ・ Sliding ring, 8 ・ ・ ・ Interlock ring, 9 ・ ・ ・ Gas release part, 10 ・ ・ ・ Stamper

Claims (7)

With a fixed side and a movable side mold facing each other,
In a substrate molding die apparatus configured to mold a main surface of a disk substrate by a stamper disposed on one of a fixed side and a movable side mold,
A heat molding apparatus for molding a substrate, wherein heat conduction on the outer peripheral side of the stamper is worse than heat conduction on the center side. 2. The substrate molding die apparatus according to claim 1, wherein one of the fixed side mold and the movable side mold has a plurality of concave portions in a region in contact with an outer peripheral portion of the stamper. One of the fixed side and the movable side mold has a heat insulating layer,
2. The apparatus according to claim 1, wherein the heat insulating layer is located near an outer peripheral portion of the stamper. One of the fixed-side and movable-side molds includes a thin film in a region in contact with an outer peripheral portion of the stamper,
2. The substrate molding die according to claim 1, wherein the thin film is made of a material having a lower thermal conductivity than a material forming the fixed or movable die. In a stamper that is arranged on one of the fixed side and the movable side molds provided in the substrate molding die apparatus and that molds the main surface of the disk substrate, the heat conduction on the outer peripheral side is smaller than that on the center side. A stamper characterized by having been made worse. 6. The stamper according to claim 5, wherein a plurality of recesses are provided on an outer peripheral portion of a surface opposite to a molding surface for molding a main surface of the disk substrate. A thin film is provided on the outer peripheral portion of the surface opposite to the molding surface for molding the main surface of the disk substrate,
6. The stamper according to claim 5, wherein the thin film is made of a material having a lower thermal conductivity than a material forming the fixed or movable mold.

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