JP2000242974A - Laminated disk substrate and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk substrate with little wobbling and having excellent mechanical characteristics such as acceleration by a laminating method to prevent intrusion of air into a disk substrate face and an adhesive face. SOLUTION: The features of this laminated disk substrate are that an adhesive layer is formed to have the outer diameter larger than the outer diameter of the recording face formed on the disk substrate 1 and smaller than the diameter corresponding to the position where the thickness of a protective layer 2 suddenly increases just inside of the outer circumference of the disk substrate 1. The adhesive layer has the thickness twice or more as much as that of the increase amt. of the thickness of the protective film 2 in the outer circumference region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk substrate having two or more disk substrates bonded together and a method for manufacturing the same. More specifically, when two or more high-density optical disk molded products are bonded together with an adhesive, a groove formed by a stamp mark of a stamper retainer formed on the disk substrate, a burr generated by a cut punch in an inner diameter portion, and an outer peripheral edge Even if there is a sudden swelling of the protective film that occurs immediately before, it is a bonding method that does not cause air entrainment between the disk substrate surface and the adhesive surface, or between the adhesives. An object of the present invention is to provide a disk substrate which has small vibration and excellent mechanical characteristics such as acceleration, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Optical disks have attracted attention because of their high density and large capacity, and have been used in various applications. For example, as an optical disc for reproduction, CD, M
There are O, CD-ROM, DVD-ROM, etc., which are used in the music field, game field, and the like. In addition, as a write-once optical disc that can be recorded only once, recording, reproduction, and the like in the field of a document filing system such as a CD-R.
Erasable MO, PD, DVD-RAM and the like are widely used mainly in the computer field.

In recent years, with the increase in the density of optical disks, disk substrates used have become thinner, and two disk substrates have been generally bonded together. As a method, a method is known in which an adhesive is applied or a sheet-like adhesive is applied to one or both recording surfaces of a disk substrate to be attached on a turntable, and the recording surfaces are attached to each other.

FIG. 2 is a cross-sectional view of a bonded product of such a high-density optical disc, and FIGS. 3 and 4 are detailed cross-sectional views of the bonded product.

In a high-density optical disk, a thin disk is used as a disk substrate to be bonded, and a general method is to bond the entire surface of the substrate to increase the bonding strength.

However, burrs on the inner peripheral portion generated during the manufacturing process, the presence of a sudden bulge immediately before the outer peripheral edge due to the protective film 2 of the recording portion 3, and the inner peripheral side surface of the stamper pressing groove due to the stamp mark of the stamper pressing. Air is trapped between the adhesive 4 and the surface of the disk substrate 1 due to the fact that the outer peripheral side is not the same as the outer peripheral side surface, resulting in an increase in surface runout of the product, deterioration of mechanical characteristics due to an increase in acceleration, etc., and a product yield. It causes a decline.

This will be described in more detail. The disk substrate 1
In many cases, injection molding is performed using a mold having a stamper installed on the fixed side, and burrs of about 5 to 20 μm are generated on the recording surface side of the inner peripheral portion due to the structure of the cut punch portion. The cavity surface Y of the stamper presser and the recording surface X of the disk are 15 to 3 to improve the fluidity and birefringence of the resin during molding.
Generally, a step of 0 μm is provided.

When a resinous protective film 2 for protecting the disk recording surface 3 is applied to the disk substrate 1,
Usually, a spin coating method is used. Since the outer peripheral portion of the disk substrate is a stamper surface, horizontal burrs are formed when the disk substrate is formed. When the protective film 2 is applied to the disk substrate recording portion 3 in this state, the protective layer within 1 mm, particularly within 0.5 mm, at the end of the outer peripheral portion becomes rapidly thick, and a phenomenon occurs that the protective layer swells by about 1 to 10 μm from the recording surface. .

When the entire surfaces of the recording surfaces X of the two disks are bonded to each other, air is entrapped between the disk substrate surface and the adhesive surface or the adhesive at the portion where the thickness has changed abruptly. The surface runout of the product increases, and mechanical characteristics such as acceleration deteriorate.

[0010]

SUMMARY OF THE INVENTION The present invention solves the problems of a method of manufacturing a disk substrate for a high-density optical disk using two or more disk substrates bonded together. Adhesive when applying or laminating the adhesive due to flash, bulging of the protective film immediately before the outer peripheral edge, and the fact that the disk recording surface is thicker than the cavity surface of the stamper holder of the disk substrate An object of the present invention is to provide a disk substrate and a method of manufacturing the disk substrate, in which air is wound around the disk substrate surface and the disk substrate after bonding is capable of preventing an increase in surface runout and preventing deterioration of mechanical characteristics such as acceleration.

[0011]

Means for Solving the Problems The present inventors have made intensive studies on such problems and found that the problems can be solved by improving the range and thickness of the adhesive layer. .

That is, the present invention relates to a bonded type disc having two or more disk substrates having a recording layer formed thereon and provided with a protective film, the protective film surfaces of which are opposed to each other, and having an adhesive layer therebetween. In the substrate, the outer diameter of the adhesive layer is larger than the outer diameter of the recording surface formed on the disk substrate and smaller than a position where the protective film suddenly becomes thicker immediately before the outer peripheral edge of the disk substrate, It is another object of the present invention to provide a bonded disk substrate, wherein the thickness of the adhesive layer is at least twice the thickness of the outer peripheral edge of the protective film.

Further, according to the present invention, the inner diameter of the adhesive layer is larger than the inner peripheral burr surface of the disk substrate, and the thickness of the adhesive layer is the height of the burr, the thickness of the outer peripheral end of the protective film. It is an object of the present invention to provide a bonded disc substrate having a thickness that is at least twice as large as the larger increment.

Further, according to the present invention, the outer diameter of the adhesive layer is smaller by 0.3 mm or more and 3 mm or less than the outer diameter of the disk substrate, and the inner diameter of the adhesive layer is smaller than the inner diameter of the disk substrate by 0 mm. 0.5 mm or more and 15 mm or less, particularly 0.5 mm or more and 1.5 mm or less smaller than the outer diameter of the disk substrate, and 5 mm or more and 10 mm or less than the inner diameter of the disk substrate. The present invention is to provide a bonded disk substrate characterized in that it is only large.

Further, according to the present invention, there is provided a laminating method wherein two or more disk substrates having a recording layer formed thereon and a protective film provided thereon are disposed so that the protective film surfaces thereof face each other and bonded therebetween with an adhesive therebetween. In the method of manufacturing a mold disk substrate, the adhesive is larger than the outer diameter of the recording surface formed on the disk substrate and smaller than the position where the protective film is suddenly thickened immediately before the outer peripheral edge of the disk substrate. A method for manufacturing a bonded disk substrate, wherein the disk substrate is bonded by applying or bonding an adhesive with a thickness of at least twice the thickness of the outer peripheral edge of the protective film in the region. Is provided.

Further, according to the present invention, the adhesive is applied to an area larger than the inner diameter of the inner peripheral burr surface of the disk substrate, the larger the height of the burr or the thickness increase of the outer peripheral end of the protective film. It is another object of the present invention to provide a method for manufacturing a bonded disk substrate, wherein the disk substrate is bonded by applying or bonding the disk substrate at a thickness of twice or more.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION As a bonded disk substrate of the present invention, a bonded disk substrate in which at least two disk substrates are bonded by an adhesive, a burr portion existing on the inner diameter side of the disk, a disk substrate It is preferable that the thickness of the adhesive layer is at least twice as large as that of the portion where the amount of change is large among the portions where the protective film applied to the recording surface has a sudden increase in thickness caused by surface tension at the outer peripheral edge of the disk substrate.

Such a bonded disk substrate can be bonded to the surface of the disk substrate and the surface of the adhesive without involving air, thereby providing an optical disk with reduced surface runout and excellent mechanical properties.

The disk substrate has an outer diameter of 30 to 30.
The disk substrate has a thickness of 0 mm and a thickness of 0.2 to 1.5 mm, and is preferably made of an acrylic resin, a polycarbonate resin, an epoxy resin, an amorphous olefin resin, a copolymer thereof, or an inorganic glass.

The disk substrate used in the present invention is injection-molded using a mold in which a stamper is installed in a fixed mold.
Burrs occur on the recording surface side in the inner diameter portion of the disk substrate.
Due to the structure of the cut punch portion, its position and size are 0.5 to 15 mm from the inner diameter side of the disk substrate, particularly 5 to 10 mm.
A burr having a height of about 5 to 20 μm is generated at a position on the outer peripheral side of mm in the recording surface direction.

The pits / grooves on the stamper surface are transferred to such a substrate, a recording film is sputtered thereon, and a protective film 2 is further provided thereon. The area immediately before the outer edge of the membrane swells rapidly,
A position of 0.3 to 3 mm at the end of the outer peripheral portion, particularly at a position of 0.3 mm from the end
The protective layer at the position of 5 to 1.5 mm rapidly increases in thickness, and a phenomenon that the protective layer expands by about 1 to 10 μm with respect to the recording surface occurs.

According to the bonded disk substrate of the present invention, the adhesive layer is provided with the burr or the protective film having a larger bulge.
By setting the thickness to twice or more and bonding the disk substrates to each other, it is possible to prevent air from being caught in the disk substrate and the adhesive surface and between the adhesives.

In this case, by using a disk substrate in which the cavity surface of the stamper retainer and the recording surface of the disk are the same surface, the laminating can be performed without air being entrapped on the cavity surface of the stamper retainer and the adhesive surface. A disk substrate can be manufactured.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A high-density optical disk substrate and a method of manufacturing the same according to an embodiment of the present invention will be described below in detail with reference to the drawings. The disk substrate 1 is made of an adhesive having a cavity surface Y of the stamper presser and a recording surface X of the disk on the same surface, and having a thickness of at least twice the height of a burr generated on the inner diameter of the disk substrate 1. By using, the laminated disk substrate of the present invention was formed.

More specifically, a stamper is mounted on a fixed die, and the inner diameter of the disk substrate 1 injection-molded using a die having the cavity surface Y of the stamper presser and the recording surface X of the disk on the same surface. 15μ high on the disk recording surface side
m, and the protective film 2 on the recording surface rapidly increased in thickness from a position 0.5 mm from the outer peripheral end of the disk, and the thickness at the final end was 6 μm higher than the recording surface X. .

When the thickness of the adhesive 4 is reduced, air is drawn between the disk substrate 1 and the surface of the adhesive 4 or between the adhesives 4.
The disk substrates were adhered to each other using a sheet-like adhesive 4 having a size m, an outer diameter of 0.5 mm smaller than the disk substrate 1, an inner diameter of 0.5 mm larger, and a thickness of 50 μm.

As a result, it is possible to form a bonded disk substrate in which air is not entrapped between the disk substrate 1 and the surface of the adhesive 4, the surface runout is 100 μm or less, and the acceleration is 4 μm.
A laminated disk substrate having mechanical characteristics of m / sec ² or less could be formed.

Similarly, the sheet was bonded using a sheet-like adhesive 4 having an inner diameter 7.5 mm larger than the inner diameter of the disk substrate 1, an outer diameter 1 mm smaller than the disk substrate 1, and a thickness of 50 μm. The bonded disc substrate could be bonded without involving air.

[0029]

As described above, according to the embodiment of the present invention, a disk substrate having two or more recording films formed thereon and having the recording surfaces bonded to each other can be used without using air. Provided. Since air is not trapped between the disk surface and the bonding surface or the bonding surface, surface runout is reduced, and a high-density optical disk substrate excellent in mechanical characteristics such as acceleration can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a bonded disk substrate obtained by bonding two disk substrates of the present invention.

FIG. 2 is a cross-sectional view of a conventional bonded disk substrate.

FIG. 3 is a detailed view of FIG. 2 in which an adhesive is applied to one surface of a conventional laminated disk substrate.

FIG. 4 is a detailed view of FIG. 2 in which an adhesive is applied to both surfaces of a conventional bonded disc substrate.

[Explanation of symbols]

 1. Disk substrate 2. 2. Protective film on recording surface Recording film 4. Adhesive A. Air pool X. Cavity side of stamper holder Disk recording surface

Claims (7)

[Claims] 1. A bonded disk substrate comprising a recording layer formed thereon, a protective film provided thereon, and two or more disk substrates having the protective film surfaces opposed to each other and having an adhesive layer therebetween. An outer diameter of the adhesive layer is larger than an outer diameter of a recording surface formed on the disk substrate, and smaller than a position where the protective film is rapidly thickened immediately before an outer peripheral end of the disk substrate; Characterized in that the thickness of the laminated disk substrate is twice or more the thickness of the outer peripheral edge of the protective film. 2. The inner diameter of the adhesive layer is larger than the inner peripheral burr surface of the disk substrate, and the thickness of the adhesive layer is the height of the burr and the thickness increase of the outer peripheral end of the protective film. 2. The laminated disk substrate according to claim 1, wherein the laminated disk substrate has a thickness that is at least twice as large as the larger one. 3. An outer diameter of the adhesive layer is smaller than an outer diameter of the disk substrate by 0.3 mm or more and 3 mm or less, and an inner diameter of the adhesive layer is 0.5 mm or more and 15 mm or less than an inner diameter of the disk substrate. Claim 1 characterized by being large
3. The laminated disc substrate according to 2. 4. An outer diameter of said adhesive layer is smaller than an outer diameter of said disk substrate by 0.5 mm or more and 1.5 mm or less, and an inner diameter of said adhesive layer is 5 mm or more and 10 mm or less than an inner diameter of said disk substrate. 4. The bonded disk substrate according to claim 3, wherein the disk substrate is large. 5. The bonded disk substrate according to claim 1, wherein said disk substrate is an optical disk substrate. 6. A bonded disc substrate in which a recording layer is formed, a protective film is formed on the disc substrate, and the protective film surfaces of two or more disc substrates are opposed to each other, and are bonded via an adhesive therebetween. In the manufacturing method, the adhesive is larger than the outer diameter of the recording surface formed on the disk substrate and the protective film is in a region smaller than a position where the protective film suddenly becomes thick immediately before the outer peripheral edge of the disk substrate. A method of manufacturing a bonded disk substrate, wherein the disk substrate is bonded by applying or bonding an adhesive with a thickness of at least twice the thickness of the outer peripheral edge of the protective film. 7. The disk substrate is coated or applied with a thickness of at least twice the height of the burr to an area larger than the inner diameter of the inner peripheral burr surface of the disk substrate. 6. The method according to claim 5, wherein the lamination is performed.