JPH11188739A - Mold for molding disk substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold capable of molding a disk substrate having no defect and good in surface properties. SOLUTION: A mold 1 for molding a disk substrate is obtained by bonding a metal plate 4 having hardness higher than that of a mold substrate 2 to the surface on the side forming the surface of the disk substrate of the mold substrate 2. Uneven predetermined patterns may be formed on the surface of the metal plate. At this time, the thickness of the metal plate is pref. 0.5 mm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk substrate molding die used for injection molding a resin disk substrate and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a disk-shaped recording medium, for example, an optical disk in which an information signal is written in advance by emboss pits, a phase change type optical disk in which an information signal is written by utilizing a phase change of a recording film, There are a magneto-optical disk on which an information signal is written using a magneto-optical effect, a magnetic disk on which an information signal is magnetically written, and the like.

[0003] These disk-shaped recording media are formed by forming a recording film or the like on a disk substrate. Here, the disc substrate is made of plastic or the like molded into a predetermined shape, and is usually molded by attaching a stamper formed into a desired shape to a mold and performing injection molding.

When manufacturing such a stamper, first, a photoresist is applied on a glass master disk, and laser cutting is performed on the photoresist so as to correspond to a desired concavo-convex pattern of a disk substrate. Thereafter, the photoresist is subjected to a development process. Thereby, a desired concavo-convex pattern is formed on the photoresist.

Next, a Ni film is formed on the photoresist thus formed by electroless plating.
The Ni film is peeled off. Finally, this Ni film becomes a stamper for forming a disk substrate.

[0006]

However, the stamper manufactured as described above has a thin film thickness of about 0.3 mm, and the stamper is liable to be distorted or undulated. For this reason, a disk substrate formed by attaching such a stamper to a mold will eventually be distorted or undulated.

In particular, in a recording medium used for an external storage device of a computer, 100 nm per several mm pitch is used.
If there is a slight distortion or surface undulation, the head on the recording medium collides with the head, causing a head crash, causing damage to the recording medium or the head, or disrupting the reproduction signal when reproducing the information signal. There is a problem that a problem occurs.

Further, it is considered that if the thickness of the stamper can be increased, it is possible to suppress distortion and undulation generated in the stamper. However, in the method of manufacturing the stamper described above, the thickness of the stamper is increased. It is very difficult. For this reason, with the stamper as described above, it was not possible to suppress the occurrence of distortion and surface undulation on the stamper, and as a result, it was not possible to form a disk substrate without distortion and surface undulation.

Therefore, as a method of forming a disk substrate free from distortion and surface undulation, a method has been proposed in which a metal die directly etched from a thick die of about 15 mm is used as a disk substrate forming die. Since such a disk substrate molding die has a sufficient thickness, distortion and surface undulation do not occur in the die.

By the way, in the method of using a directly etched mold as a mold for forming a disk substrate, a sintered material is used as a material of the mold.
However, since pores exist inside the sintered material, if the sintered material is used as it is as a mold, when the disc substrate is molded, the disc substrate on the molded disc substrate corresponds to the hole portion when molded. Protrusions are formed on the surface.

Such a projection causes the above-described head crash in a recording medium in which recording and reproduction are performed while the magnetic head is slightly floated, for example. In addition, in order to achieve high-density recording of a recording medium, the flying height of the head slider needs to be as small as possible, and it is necessary that there is no protrusion having a height of, for example, 50 nm or more on the disk substrate. Therefore, a method in which the sintered material is used as it is as a material for the mold and directly etched from the mold is used as a mold for molding a disk substrate is not preferable in terms of high-density recording of a recording medium. .

Further, in this sintered material, when etching is performed, irregularities due to the etching are apt to vary, and unnecessary irregularities are likely to occur. Therefore, even if there are no pores in the sintered material, a disk substrate forming die using the sintered material as it is as a die material accurately forms a disk substrate having a fine pattern. It is difficult.

As described above, in the method in which the sintered material is used as it is as a material for the mold, and this mold is directly etched and used as a mold for molding a disk substrate, the disk substrate is accurately formed. Could not.

Therefore, as a method of using a directly etched mold as a mold for forming a disk substrate, a sintered material is used as the material of the mold substrate, and there is no void inside the mold substrate and the mold is etched. There has been studied a method of forming a metal film that does not cause variations in the pattern, and etching the metal film so as to correspond to a desired concavo-convex pattern of a disk. By using such a disk substrate molding die, the above-described problem can be avoided.

Here, means for forming a metal film on the mold substrate include, for example, plating, vacuum deposition, and sputtering. However, the density of the metal film to be formed and the mold substrate Sputtering is desirable in consideration of the adhesive force of the sputtering.

However, the metal film thus formed on the mold substrate is not completely uniform in film thickness. for that reason,
When using the disk substrate molding die, it is necessary to polish the surface of the metal film before forming the disk substrate so that the surface of the metal film has an appropriate surface roughness and flatness. , Poor production efficiency.

Further, as described above, the disk substrate forming die 60 manufactured by forming the metal film 51 on the die substrate 50, as shown in FIG. If foreign matter 52 such as dust adheres to the surface, the foreign matter 5
2, a metal film 51 is formed. Then, as shown in FIG. 9, after the metal film 51 is formed, the foreign matter 52 may be peeled off, and a pinhole 53 may be formed in that part. Thus, when the pinhole 53 exists,
At the time of molding, the pinhole 53 is transferred onto the disk substrate, and a projection-like defect occurs on the molded disk substrate.

Accordingly, the present invention has been proposed in view of the conventional circumstances, and is a disk substrate molding capable of molding a disk substrate having good surface properties without defects such as distortion, surface waviness, and pinholes. It is an object to provide a mold.

[0019]

DISCLOSURE OF THE INVENTION A disk substrate molding die according to the present invention, which has been completed to achieve the above-described object, has a structure in which a disk substrate surface of a die substrate is formed.
It is characterized in that a metal plate having a higher hardness than the mold substrate is bonded via an adhesive layer.

On the surface of the metal plate, a predetermined pattern of irregularities may be formed. At this time, the thickness of the metal plate is preferably 0.5 mm or more.

In the disk substrate molding die according to the present invention constructed as described above, a metal plate having a higher hardness than the die substrate is bonded to one principal surface of the die substrate via an adhesive layer. It has been done. As described above, in the disk substrate molding die according to the present invention, a metal plate having a smooth surface and a sufficient thickness is adhered to the die substrate, and this metal plate is a surface on which the disk substrate is formed. .

Therefore, the mold for molding a disk substrate according to the present invention has good surface properties without defects such as distortion, surface waviness and pinholes on the mold surface. As a result, according to the disk substrate molding die according to the present invention, a disk substrate having no defects and good surface properties is molded.

Further, according to the disk substrate molding die of the present invention, since a predetermined pattern of irregularities is formed on the surface of the metal plate, a predetermined pattern corresponding to a signal such as an information signal is formed. Disk substrate is formed with high precision. Furthermore, in the disk substrate molding die according to the present invention, the metal plate is less likely to warp when the thickness of the metal plate is 0.5 mm or more.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings.

A mold for molding a disk substrate to which the present invention is applied is a mold for manufacturing a resin disk substrate used for a recording medium such as an optical disk, a magneto-optical disk, a phase change disk, and a magnetic disk by injection molding. It is. FIG.
1 is a perspective view of a disk substrate molding die to which the present invention is applied.

As shown in FIG. 1, a disk substrate molding die 1 to which the present invention is applied includes a die substrate 2 provided in an injection molding apparatus and an adhesive formed on the die substrate 2. Layer 3
And a metal plate 4 bonded to the mold substrate 2 via the adhesive layer 3.

The mold substrate 2 has a cylindrical substrate support member having an outer diameter slightly larger than the outer diameter of the disk substrate to be molded on a disk-shaped mounting portion 2a to be mounted on the injection molding apparatus. 2b are integrally formed. A center hole having a diameter slightly larger than the inner diameter of the disk substrate to be formed is formed in the center of the substrate support member 2b. The mold substrate 2 is adhered to a metal plate 4 forming one main surface of the disk substrate via an adhesive layer 3 and supports the metal plate 4.

The material of the mold substrate 2 is Fe, Cr,
A sintered material containing at least one of V, C, Mo, Si, and Mn is preferable, and particularly contains Fe at a ratio of 75% by weight or more and Cr at a ratio of 20% by weight or less. Sintered materials are more preferred. Specifically, Fe
75.6% by weight, C 17% by weight, Si 0.4% by weight, Mn 0.3% by weight, Cr 18% by weight, Mo 1.0% by weight, V 3.0% by weight Contained sintering material.

The adhesive layer 3 has a disk shape having a bottom surface having substantially the same diameter as the outer diameter of the mold substrate 2, and is formed on the mold substrate 2. In the center of the adhesive layer 3, a center hole having substantially the same diameter as the inner diameter of the mold substrate 2 is formed.

As the material of the adhesive layer 3, a material having a melting point higher than the temperature of the mold substrate 2 or the temperature of the metal plate 4 at the time of molding, for example, 130 ° C. or higher is preferable. This is to prevent the material of the adhesive layer 3 from being melted at the time of molding because the temperature of the mold substrate 2 and the metal plate 4 becomes 130 ° C. or more at the time of molding. Specifically, the material of the adhesive layer 3 is preferably made of a material containing at least one of In, Sn, and solder.

The metal plate 4 has a disk shape having an outer diameter substantially equal to the outer diameter of the mold substrate 2. The metal plate 4 is bonded onto the mold substrate 2 via the adhesive layer 3 and is supported by the mold substrate 2. In the center of the metal plate 4, a center hole having substantially the same diameter as the inner diameter of the mold substrate 2 is formed.

As the material of the metal plate 4, similarly to the target used for sputtering, a high-density and high-purity material produced by melting in a vacuum is preferable. Moreover,
The hardness of the metal plate 4 is preferably higher than the hardness of the mold substrate 2. Above all, Ir is preferable as the material of the metal plate 4 from the viewpoint of high hardness and excellent thermal stability. For example, this Ir is made about 99.9% pure by melting in a vacuum. Such a high-density and high-purity material has very few holes. Therefore, by using the above-described material as the material of the metal plate 4, it is possible to manufacture the disk substrate molding die 1 having a smoother surface and excellent surface properties.

The thickness of the metal plate 4 is preferably 0.5 mm or more. This is because the metal plate 4 is less likely to warp.

Further, by forming irregularities of a predetermined pattern on the surface of the metal plate 4 by etching or the like, it is possible to obtain the disk substrate molding die 1 on which a predetermined pattern corresponding to a signal such as an information signal is formed. .

The disk substrate molding die 1 to which the present invention is applied as described above has a higher hardness than the die substrate 2 on one main surface of the die substrate 2 via the adhesive layer 3. The metal plate 4 is bonded. As described above, in the disk substrate molding die 1 to which the present invention is applied, since the metal plate 4 having a smooth surface and a sufficient thickness is formed as the disk substrate forming surface, distortion and undulation are generated on the surface. And good surface properties.

In addition, since the metal plate 4 is bonded to the die substrate 2 via the adhesive layer 3 in the disk substrate molding die 1, even if foreign matter adheres to the die substrate 2. Since the adhesive layer 3 covers the foreign matter, it is possible to avoid a phenomenon that the foreign matter is peeled off and a pinhole is formed.

The disk substrate molding die 1 is provided with an adhesive layer between the metal plate 4 and the die substrate 2 even if the surface of the die substrate 2 becomes uneven due to foreign matter adhering to the die substrate 2. Because of the presence of 3, the influence of the unevenness on the surface of the mold substrate 2 on the surface of the metal plate 4 can be effectively suppressed.

Therefore, the disk substrate molding die 1 to which the present invention is applied is free from defects such as distortion, surface waviness and pinholes on the die surface, and has good surface properties. As a result, according to the disk substrate molding die 1 to which the present invention is applied, it is possible to mold a disk substrate having no surface defect and having good surface properties.

Next, a method for manufacturing a disk substrate molding die to which the present invention having the above-mentioned structure is applied will be described in detail. FIGS. 2 to 6 are schematic diagrams showing the manufacturing process of the disk substrate molding die.

In order to manufacture the disk substrate molding die 1, first, as shown in FIG. 2, a die substrate 2 having a flat surface 2c serving as a reference surface for forming a disk substrate surface is prepared.

Next, as shown in FIG. 3, an adhesive metal 3a is disposed on the surface 2c of the mold substrate 2, and the adhesive metal 3a is heated and melted to a temperature equal to or higher than the melting point.

On the other hand, as shown in FIG. 4, a disk-shaped metal plate 4 having a bottom surface having substantially the same size as the mold substrate is prepared in advance. Then, the metal plate 4 is placed on the bonding metal 3a in the above-mentioned molten state, and the mold substrate 2 is gradually cooled while gradually applying a load to the bonding metal 3a.
And the metal plate 4 are bonded. At this time, the bonding metal 3a is cured to form the adhesive layer 3 shown in FIG.

Next, an extra portion is provided between the mold substrate 2 and the metal plate 4 such that the inner and outer diameters of the metal plate 4 are arranged so as to exactly overlap the inner and outer diameters of the mold substrate 2, respectively. A process for removing the leaked bonding metal 100 is performed.

Next, the surface of the metal plate 4 is polished and smoothed using a polishing apparatus 41 as shown in FIG.

Here, the polishing apparatus 41 will be described below. As shown in FIG. 6, the polishing apparatus 41 supports a disk-shaped polishing member 42 provided with a polishing surface and a polishing member 42 which is disposed opposite to the polishing member 42 while applying a load to the material to be polished. And a slurry sprayer 44 for spraying a slurry made of an abrasive.

The polishing member 42 has a disk shape, and one main surface 42a is a polishing surface. The polishing member 42 is configured to rotate in a direction indicated by an arrow x in FIG.

The load applying member 43 is provided on the mold substrate 2 disposed on the polishing member 42 such that the surface to be polished of the mold substrate 2 as the material to be polished is in contact with the polishing member 42 without any gap. You. During the polishing, the mold substrate 2 is rotated by a driving source (not shown) in the direction of the arrow y in the figure, and is moved by another driving source (not shown) in the direction of the arrow z, which is the radial direction.

A slurry 45 made of an abrasive is enclosed in the slurry sprayer 44. The slurry sprayer 44 sprays the slurry 45 during polishing.

When the metal plate 4 is polished using the polishing apparatus 41 having such a structure, first, the metal substrate 4 to which the metal plate 4 is adhered as shown in FIG. Installed so as to face.

Next, the polishing member 42 is rotated by a driving source (not shown) in the direction of the arrow x in the figure, and the slurry is sprayed from the slurry sprayer 44.

At this time, while the mold substrate 2 to which the metal plate 4 is adhered is rotatably supported by a driving source (not shown) in the direction of the arrow y in the figure, it is moved in the direction of the arrow z by the other driving source (not shown). Thus, the entire surface of the metal plate 4 is uniformly polished by the polishing surface of the polishing member 42.

As described above, the surface of the metal plate 4 is polished to finally form the disk substrate molding die 1 shown in FIG.

Further, depending on the specification of the disk, a desired concavo-convex pattern is formed on the surface of the metal plate 4 by etching to obtain a disk substrate molding die.

Next, a description will be given of an injection molding apparatus provided with the disk substrate molding die 1 according to the present invention manufactured as described above. FIG. 7 is a sectional view showing a main part of an injection molding apparatus 10 in which a disk substrate molding die 1 to which the present invention is applied is arranged.

The injection molding apparatus 10 includes a fixed mold 1a forming one main surface of a disk substrate, and a movable mold disposed opposite to the fixed mold 1a and forming the other main surface of the disk substrate. The mold includes a mold 1b and an outer peripheral mold 12 forming an outer peripheral side surface of the disk substrate.

Here, the fixed mold 1a and the movable mold 1b
Is a disk substrate molding die 1 to which the present invention shown in FIG. 1 is applied.

The movable mold 1b is supported by guide means (not shown), and moves toward and away from the fixed mold 1a by a driving mechanism.

The outer peripheral mold 12 includes a fixed outer peripheral mold 12a for fixing the fixed mold 1a in the injection molding apparatus 10, and a movable outer peripheral mold 12b for fixing the movable mold 1b in the injection molding apparatus 10. Is provided. The outer peripheral side surface of the disk substrate formed by the outer peripheral mold 12 is formed.

The fixed mold 1a and the movable mold 1
The b and the outer peripheral mold 12 form a cavity 11 that cooperates in a clamped state to form a disk substrate.

On the side of the fixed mold 1a, a nozzle 1 is located at the center of the cavity 11 for molding the disk substrate and injects and melts the molten synthetic resin material into the cavity 11.
4 is provided. Then, the molten synthetic resin material is injected and filled into the cavity 11 through the nozzle 14 at high pressure.

On the other hand, the cavity 1 is provided on the movable mold 1b side.
A first eject member 16 provided at a position corresponding to the center of the first unit 1 is disposed movably in the axial direction. The first ejecting member 16 is formed in a cylindrical shape having an outer diameter corresponding to a region on the inner peripheral side of the disk substrate to be formed where the information signal is not recorded.

Then, the first eject member 16
During the releasing operation of the disk substrate, the disk substrate formed by being projected into the cavity 11 by a driving means (not shown) is projected from the movable mold 1b and released.

The first eject member 16 is provided with a punch 17 for forming a center hole of a disk substrate formed on the inner peripheral side thereof. The punch 17 is moved in the same axial direction as the first eject member 16 by a drive mechanism (not shown). And this punch 17
The drive mechanism protrudes into the cavity 11 to form a center hole in the center cutting region of the disk substrate.

Further, on the inner peripheral side of the punch 17, a second
The eject member 18 is mounted to be able to move forward and backward by a hydraulic mechanism. Then, the second ejection member 1
Reference numeral 8 denotes an end face on the side of the cavity 11 constituting a resin stay 18a. The second eject member 18 is disposed movably in the axial direction, similarly to the first eject member 16. Therefore, the synthetic resin material injected and filled from the injection port of the nozzle 14 is injected toward the bottom of the resin stay 18a, and is uniformly filled in the cavity 11. Then, after the center hole of the disk substrate is formed by the punch 17, the second eject member 18 protrudes the synthetic resin material of the cut portion from the movable mold 12b and releases it. In the injection molding apparatus 10 configured as described above, first, by operating a drive mechanism (not shown), the movable mold 1b moves closer to the fixed mold 1a to be in a mold-clamped state, and the surroundings are changed. A closed cavity 11 is formed.

Next, the synthetic resin material melted from the nozzle 14 of the sprue bush 15 is injected and filled into the cavity 11 in this mold clamping state. Then, in a state where the synthetic resin material is cooled to a semi-molten state by a temperature adjusting mechanism (not shown) provided in the injection molding apparatus 10, a punch 17 is inserted through the center hole of the first eject member 16.
Is projected in the direction of the fixed mold 1a to form a center hole of the disk substrate to be molded.

Thereafter, in the injection molding apparatus 10, the injection-filled synthetic resin material is cooled and hardened by a temperature control mechanism (not shown).

In the injection molding apparatus 10, a driving mechanism (not shown) operates to move the movable mold 1b to the fixed mold 1a.
, The mold opening operation is performed. Finally, the disk substrate molded in the cavity 11 is moved by the first ejecting member 16 operating in a state where the fixed mold 1a and the movable mold 1b are opened. It is taken out by a disc substrate taking out mechanism (not shown) protruding from the side 1b.

In the injection molding apparatus 10, the disk substrate molding die 1 to which the present invention is applied may be used for either the fixed die 1a or the movable die 1b.

As described above, the metal plate 4 is
Is adhered by the adhesive layer 3 so that the metal plate 4 having a smooth surface and a sufficient thickness is used as the surface for forming the disk substrate, so that there is no defect such as distortion, surface undulation or pinhole. A disk substrate molding die having good surface properties can be manufactured. As a result, according to the disk substrate molding die to which the present invention is applied, it is possible to mold a disk substrate having good surface properties without defects such as distortion, surface undulations and pinholes, and obtaining higher reliability. Can be.

[0070]

As described above in detail, according to the disk substrate molding die according to the present invention, the hardness is higher than that of the die substrate on one main surface of the die substrate via the adhesive layer. It is formed by bonding a metal plate. As described above, in the disk substrate molding die according to the present invention, the metal plate having a smooth surface and a sufficient thickness is formed as the disk substrate forming surface, so that the surface has distortion, surface undulation, pinholes, and the like. With no defects and good surface properties.

Accordingly, the disk substrate molding die according to the present invention has good surface properties without defects such as distortion, surface waviness, and pinholes on the die surface, and as a result, has good surface properties and high surface properties. A disk substrate with high reliability can be formed.

Further, according to the disk substrate molding die of the present invention, since the predetermined pattern of irregularities is formed on the surface of the metal plate, the predetermined pattern corresponding to a signal such as an information signal is formed. The molded disk substrate can be formed with high precision.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a disk substrate molding die to which the present invention is applied.

FIG. 2 is a perspective view showing a mold substrate used in a disk substrate molding mold to which the present invention is applied.

FIG. 3 is a perspective view showing a state in which an adhesive layer is formed on a mold substrate in a method of manufacturing a disk substrate molding mold to which the present invention is applied.

FIG. 4 is a perspective view showing a step of bonding a metal plate onto a die substrate via an adhesive layer in a method of manufacturing a disk substrate molding die to which the present invention is applied.

FIG. 5 is a perspective view showing a state in which a metal plate is adhered to a mold substrate via an adhesive layer in a method of manufacturing a disk substrate molding mold to which the present invention is applied.

FIG. 6 is a cross-sectional view showing a step of polishing a metal plate in a method of manufacturing a disk substrate molding die to which the present invention is applied.

FIG. 7 is a sectional view showing a main part of the injection molding apparatus.

FIG. 8 is a cross-sectional view showing a state in which a foreign substance adheres to a substrate in a conventional disk substrate molding die having a metal film formed on a die substrate.

FIG. 9 shows a disk substrate molding die shown in FIG.
FIG. 4 is a cross-sectional view showing a state in which a foreign substance has peeled off and a pinhole has been formed in that portion.

[Explanation of symbols]

1 mold for disk substrate molding, 2 mold substrate, 3
Adhesive layer, 4 metal plates

Claims (8)

[Claims] 1. A disk substrate, comprising: a metal substrate having a higher hardness than the die substrate is bonded via an adhesive layer on a surface of the die substrate on which a disk substrate surface is to be formed. Mold for molding. 2. A disk substrate molding die according to claim 1, wherein a predetermined pattern of irregularities is formed on a surface of said metal plate. 3. The disk substrate molding die according to claim 1, wherein said metal plate is made of a material containing at least Ir. 4. The disk substrate molding die according to claim 1, wherein said metal plate has a thickness of 0.5 mm or more. 5. The disk substrate molding die according to claim 1, wherein the adhesive layer is made of a material having a melting point higher than the temperatures of the die substrate and the metal plate when the disk substrate is molded. . 6. The disk substrate molding die according to claim 5, wherein said adhesive layer is made of a material containing at least one of Sn, In, and solder. 7. The method according to claim 7, wherein the mold substrate is made of Fe, Cr, V, C,
2. The disk substrate forming die according to claim 1, wherein the die is made of a sintered material containing at least one of Mo, Si, and Mn. 8. The disk substrate forming metal according to claim 7, wherein said sintered material contains Fe in a proportion of 75% by weight or more and Cr in a proportion of 20% by weight or less. Type.