JPS5998331A - Substrate for optical disk - Google Patents

Abstract

PURPOSE:To obtain a substrate for a disk causing no deformation and having a long life by successively laminating the 2nd org. material layer which is larger than the average width of grooves in an optical disk for tracking and the 1st org. material layer cast in a casting mold on a hard substrate of chemically tempered glass or the like. CONSTITUTION:A metallic die 1 having grooves for tracking is uniformly wetted with methyl acetate, a cellulose acetate sheet 3 is stuck to the die 1 to form a layer 2 dissolved in methyl acetate, and methyl acetate is evaporated to cure the layer 2. An epoxy adhesive 4 is applied to the sheet 3, and chemically tempered glass 5 is stuck. After separating the die 1, a recording film 8 of an As-Te-Se alloy or the like is formed on the layer 2 by vapor deposition. Spacers 6 are then stuck along the axial hole and the peripheral side of the resulting disk, and chemically tempered glass 7 for protection is stuck. Light for recording or readout is allowed to enter the disk from the glass 5 side. The deformation of the disk is prevented because of the increased strength, and scratch resistance is provided to the surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a 16-disk substrate, which is a recessed optical disk substrate made of a hard material such as chemically strengthened glass.

)+6 Disc substrates have conventionally been made of glass, vinyl, vinyl chloride, and vinyl acetate polymers. Usually, in the case of materials mainly containing vinyl chloride, press method, polymethyl methacrylate-1-
Injection molding is used for products that mainly contain In these cases, a hard mold made of nickel or other material is made from the irregularities of the original disc with the grooves formed.

The grooves are replicated by pressing or pouring heated organic matter onto this. However, such organic materials that can be manufactured are easily deformed even at room temperature, and their surfaces are easily scratched.

Made of hard material that does not easily deform under mechanical pressure.

)1・v11 gQJ is said to be effective in preventing deformation and scratches by bonding with a material that is easy to produce. However, since there is usually a difference in coefficient of thermal expansion between these materials, unless one of the materials is made thinner, the material will warp as the temperature changes, making faithful reproduction impossible. However, when the soft material that can be easily reproduced is thin, conical shapes are used to reproduce the irregularities using a press method or an injection molding method.

An object of the invention is to provide an extremely stable and long-lasting optical disk substrate that does not have the drawbacks described in 1-6 above.

The '6 disk substrate of the present invention has the following IJ, 11 structure.

2J from hard materials such as chemically strengthened glass
〃, a second organic material i′1 layer having a +pτ depth of 1 to an average width of 47+G of the unevenness for racking on 1 part of the board;
41011 and the first organic material layer is at least a free layer.

The present invention consists of two organic material layers in ()> of li. First, 1) Dissolving the iC shade material M film with an organic solvent at room temperature. l tsurui l l (viscosity organic material solution 1
~TF' for Ratsuking? Or is the shape of the groove or hole accurate because it is spread to every corner of the hole and then assimilated?
+! l.

It is actually transcribed. Moreover, since the second organic material F) thin film layer is formed on the first organic material thin layer 1- with a predetermined thickness, mechanical strength is maintained.

In addition, since it is formed in this way, it does not introduce warping, distortion, cracks, etc. even when bonded to a substrate, and has excellent characteristics such as high sensitivity and small recording holes.
,ru.

This will be explained in detail below using examples.

18 to 1f are schematic diagrams of the manufacturing process of an optical disk substrate as an embodiment of the present invention.

All figures are cross-sectional views of the substrate. The board is circular.

This is an example in which there is an opening in the center through which the rotating shaft passes.

Thickness as a hard material substrate], , ] mm, outer diameter 3
30mn1. Chemically strengthened glass with an inner diameter of 70 mm by ion exchange method and a soft organic thin film with a thickness of 0.
A cellulose acetate membrane of 05n++++ was prepared in advance.

First, methyl acetate 2 was poured into a mold 1 having groove-like irregularities, which is a tracking guy Y, to uniformly wet the mold 1, and 3 was attached to a cellulose acetate sheet 1.

At this time, cellulose acetate-I dissolved in methyl acetate
~ forms layer 2 and is assimilated. Next, epoxy adhesive 4 is applied to the opposite side of this cellulose acetate sheet, and the above chemically strengthened glass 5 is pasted. Next, when mold 1 was peeled off from one end, cellulose acetate 1-
3 remained on the chemically strengthened glass side, and the side with a) was exposed. Next, this substrate was placed in a vacuum deposition apparatus, and an A'5-te-8e recording film 8 was deposited on the cellulose acetate layers 1 to 2 to a thickness of about 4.0 m. Next, a part of the periphery of the film 8 is wiped with Acetone iJ]. Next, paste a spacer 6 with a thickness of 0.1 mm on the inner and outer peripheries of this disk on the side on which the vapor-deposited film is attached. 1 digit to attach tempered glass 7.

Even with this chemically strengthened glass, it is good to attach some kind of sheet (not shown) to the opposite surface of the chemically strengthened glass. The adhesion will be stronger if the spacer 6 is not provided with the alumina sheet 1~ or the cellulose acetate sheet 1~.

Even if the laser beam for recording and reading is incident from the chemically strengthened glass 5 side, which is a transparent substrate, the protective chemically strengthened glass 7
The light may be input from ff111.

Chemically strengthened glass can be recycled and has high strength, making it ideal for substrates and protection.

The bonding of chemically strengthened glass and cellulose acetate 1 to others is not limited to the method using the adhesive described above,
Various methods can also be used, such as a method of applying a solvent, pasting and solidifying, and thermocompression bonding. This is L2, -,)
The details will be explained later. In addition, cellulose acetate-1 described in
In addition to -, any type of organic substance that is rapidly assimilated after being dissolved in a solvent can be used.

Further, as described in 81-81, since the disk of the present invention mainly uses a hard material such as chemically strengthened glass for the substrate, it is not easily deformed, scratched, and does not change over time. This chemically strengthened glass is made by adding atoms with a large radius to the glass surface using ion exchange methods.

Strength is increased by introducing molecules, ions, etc. to create compressive stress.

28 to 2e are schematic diagrams showing the manufacturing process of an optical disk substrate according to another embodiment of the present invention.

As a board made of hard material, the thickness is 11TIITl and the outer diameter is 330mm.
mm, a donut-shaped PMMA plate with an inner diameter of 70 mm+, and two types of cellulose acetate 1 to 1 with different concentrations (weight ratio of solvent and solute) or solute molecular weight as a soft organic thin film.
Prepare a solution (the solvent is cyclohexanone). First, a cellulose acetate-1 solution with a concentration or molecular weight suitable for obtaining a thin film is applied to the mold 21 having irregularities using a spinner to an average film thickness of about 150 nm, and dried.
A first coating layer 22 was used (2a). Next, a high viscosity cellulose acetate solution suitable for obtaining a thick film, for example, is poured into the above PMMA temporary 21+).
5 was pressed from one end to prevent air bubbles from appearing until it was completely stuck (buta (2c:). After the second cellulose acetate layer 1 to layer 2:3 had solidified, it was separated from the mold 21. (2d). If the mold 21 has information such as video, audio, digital, etc., the information can be read out as it is by depositing metal on the uneven surface of the replica thus formed.Mold 21 In the case of 1 to 1 to have unevenness for a racking guide, the replica formed in this way is used as a substrate, an information recording member is adhered thereon, and the information can be recorded in the same manner as in Example 1 described above. It can be made into a disk (2e). Note that 26 is a spacer and 27 is a protective chemically strengthened glass.The thickness of cellulose acetate 23 is 0-5 m, which is 1/2 of the thickness of PMMΔ+Fi25.
mf! : If the thickness is exceeded, a large warpage will occur after separation from the mold, making recording and reading difficult, so the thickness must be less than this. On the other hand, if the average thickness of the cellulose acetate layer 23 is less than 80 nm, which is the average amplitude of the unevenness, the thickness of the cellulose acetate layer at the bottom of the unevenness will be uneven, so that a further thickness is required. It is. In addition, when cellulose acetate 1 layer 23 becomes particularly thin, PMMAJ
It is even better to use an ultraviolet curing adhesive (for example, trade name: Fo1-Bond) to attach fi25.

In this example, cellulose acetate-1~ dissolved in a solvent was used, but a monomer or a low molecular weight material could also be applied.
It is even better to use polymerization because the process can be simplified.

A more preferable average thickness of the cellulose acetate layer 23 is in the range of 300 nm or more and 2200 μm or less. This is common to all organic thin film layers forming layer 23.

In addition to P M M Δ, in addition to the chemically strengthened glass mentioned above, other resins that are difficult to deform, such as CR-39 (borezi glycol diallyl carbonate), ABS resin, and AS
A resin (acrylonitrile/styrene 4'11 resin) or the like may also be used.

As described in detail above, the present invention provides an excellent optical disc or optical disc by providing two organic thin film layers of a predetermined thickness on a hard substrate such as chemically strengthened glass.
．． l', Sakagaga 17) is an industrial profiteer. In addition to the method described in Example A3, it is not impossible to form the right rock layer having irregularities by a pressing method (also called compression, embossing, etc.). Further, those skilled in the art will easily infer that the present invention is also applicable to a disc in which reading is performed using a probe. Using chemically strengthened glass for the substrate is also effective for thermomagnetic recording disks and magnetic disks.

[Brief explanation of the drawing]

Figure 1 tJ Manufacturing process of one embodiment of the present invention I Schematic diagram, Figure 2
The figure is a schematic diagram of the manufacturing process of another embodiment of the present invention. 1... Mold, 2. First cellulose acetate 1 to layer,
3... Second cellulose acetate layer, 4... Adhesive layer, 5... Chemically strengthened glass, 6... Spacer, 7
... Chemically strengthened glass for protection, 8 ... Information recording member (
As Figure 1 (1d) (1d) Figure 2 I (2d) Hitachi, Ltd. Central Research Laboratory, 1-280 Higashikoigakubo, Kokubunji City

Claims (1)

[Scope of Claims] A second organic material layer having a film thickness on the upper part of a predetermined plate-like substrate whose thickness is determined by the average amplitude of the unevenness so that the ranking is 1, and a first organic material formed into the mold with an injection port. For an optical disk, the layer is at least 1r+H layer.