JP2941313B2 - Optical disc manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an optical disk for optically recording information.

[Related Art] An optical disk is an information recording medium having a high density and a high recording capacity, and is used for a document file, an image file, a memory for a computer, and the like, so that the required reliability is extremely high.

The structure of the optical disk includes the following types.

Single-plate structure with a recording film attached to a substrate made of a transparent material Air-sandwich structure in which two single-plate optical disks are attached to the inner and outer peripheries with an adhesive via spacers Two-plate structure The optical disk having the highest reliability among them has a two-layer type structure having a large bonding area. Mechanical strength (shock resistance, peeling resistance), weather resistance (humidity resistance, temperature resistance)
This is because it is excellent in warpage.

By the way, the conventional optical disk is shown in FIGS. 3 (a) to 3 (d).
Was manufactured by the process shown in FIG. That is, in FIG. 3A, a recording film 4 is formed on a transparent disk-shaped substrate 2 by vacuum evaporation, sputtering, or the like. Then
This is placed on a turntable 6 through a center ring shaft 5 as shown in FIG. 3 (b), and a photo-curable adhesive or a two-component mixed-curable adhesive 7 is applied by a coating nozzle 13 while rotating. The adhesive 7 is thinly spread on the recording film 4 on the surface of the substrate 2.

Next, as shown in FIGS. 3 (c) and 3 (d), the protective substrate 8 and the substrate 2 are overlapped and pressed with a pressure plate 10, or the adhesive 4 is spread by centrifugal force due to spin. Lamination is performed.

[Problems to be Solved by the Invention] However, in the method of manufacturing an optical disk according to the conventional technology, a highly accurate center hole diameter formed at the time of manufacturing a substrate and
Spiral shape with a width of 1.0 to 2.0 μm provided on the recording surface,
Alternatively, the amount of eccentricity between the concentric recording / reproducing guide groove and the center hole is such that the adhesive 15 protrudes from the end face of the substrate center hole 1 due to the bonding of the substrate 2 and the protection substrate 8 and is hardened. If the accuracy of the inner diameter of the center hole 1 deteriorates, it becomes difficult to mount the center hole 1 on a recording / reproducing apparatus, and furthermore, the amount of eccentricity between the center hole 1 and the guide groove for recording / reproduction increases, so that recording / reproduction is impossible. Had a problem.

In other words, it is difficult to adjust the amount of adhesive applied to a very small area, and if the amount of adhesive applied is small, the adhesive will not spread uniformly even in spin coating, etc. The adhesive will need to be applied in some excess, as this will make it more difficult. The average thickness of the adhesive after curing is about 100 μm.
The adhesive had an allowable width of 0 to 30 μm, and even within this allowable width, the adhesive easily protruded from the center hole 1 due to subtle changes in the pressing force and the pressing time.

For this reason, there has been a serious problem that the adhesive protruding from the center hole 1 adheres to the centering shaft 5 and is hardened. These issues are summarized as follows.

When the adhesive adheres to the centering shaft 5 and cures,
First, it is difficult to remove the substrate 2 from the centering shaft 5, and if it is forcibly removed, the optical disk will be broken. Therefore, the yield is poor.

Even if the centering shaft 5 is removed, the hardened adhesive 15 that has protruded into the center hole 1 must be removed by cutting or the like. Post-processing such as cutting
The cost increases due to an increase in man-hours.

In addition, each time the centering shaft 5 is used, the cured adhesive adhered to the centering shaft 5 is removed, so that cleaning is necessary each time the centering shaft 5 is used. It has to be used while replacing, and the productivity deteriorates.

Further, even if the amount of the adhesive 4 is adjusted to prevent the adhesive 4 from protruding or adhering to the centering shaft 15,
Since it is difficult to spread the adhesive 4 all over and uniformly, there is also a problem that sufficient bonding cannot be performed.

An object of the present invention is to eliminate the above-described problem, regulates the spread of the adhesive in the direction of the inner peripheral portion center hole at the time of bonding, and allows two sheets of the adhesive without protruding from the substrate center hole. An object of the present invention is to provide a method of manufacturing an optical disk with high productivity to which substrates can be bonded.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following constitution.

That is, the method for manufacturing an optical disk of the present invention selectively provides a recording film on a portion of at least one of the two transparent substrates having a central hole except for an inner peripheral portion of one principal surface of the transparent substrate. Forming a light transmitting portion on the inner peripheral portion;
After applying an adhesive having photo-curing properties to the recording film side of the substrate, the other transparent substrate is superimposed, and further, a light-transmitting light transmitting the light for curing the adhesive from the light-transmitting portion to the inner peripheral portion. A pressure plate having a region is pressed from the main surface opposite to the main surface on which the recording film is formed of the transparent substrate on which the recording film is formed to spread the adhesive, and the light is transmitted to the light transmitting portion through the light transmitting region. By irradiating the adhesive, the adhesive spread on the portion corresponding to the light transmitting portion is immediately light-cured, and thereafter, the adhesive in the other uncured portion is cured.

In the present invention, it is preferable to use a curable resin combined with light and heat as the liquid adhesive having photocurable properties.
Further, in the present invention, it is particularly preferable to use an ultraviolet-curable resin or an ultraviolet-heat-curable resin as the adhesive.

[Operation] As described above, the first method of manufacturing the optical disk of the present invention.
In the step, a recording film is selectively formed on at least one inner surface of one main surface of at least one of the two transparent substrates having a center hole at a center portion, and the recording film side of the substrate is formed. After applying an adhesive having photo-curing properties to the substrate, the substrates are superimposed, and a pressure plate having a transmission region through which light for curing the adhesive is transmitted from the light-transmitting portion to the inner peripheral portion is formed on the transparent substrate on which the recording film is formed. The pressure is applied from the main surface opposite to the recording film forming main surface to spread the adhesive, and at the same time, simultaneously irradiating the light transmitting portion with light, the adhesive spreading to the portion corresponding to the light transmitting portion Is immediately light-cured and two transparent substrates are first superimposed. That is, since the adhesive spreading on the portion corresponding to the light transmitting portion is simultaneously light-cured, it is possible to restrict the adhesive from spreading in the inner circumferential direction from the light transmitting portion. The reason is that the photo-curing reaction generally occurs instantaneously as a radical reaction and stops the flow of the adhesive in a very short time.

The second step of the present invention is to subsequently cure the adhesive in the entire other uncured portion.

As described above, the adhesive is cured in the light-transmitting portion around the central portion and does not spread further toward the central hole,
The two substrates can be bonded together without protruding the adhesive from the end face of the substrate center hole, and the productivity can be greatly improved.

Example An example of the present invention will be described below with reference to the drawings. Parts corresponding to those in the conventional example are denoted by the same reference numerals.

1 (a) to 1 (e) show a first embodiment of a method for manufacturing an optical disk according to the present invention, and are bonding process diagrams of an optical disk capable of recording and reproducing on one side only from a full-contact structure.

In FIG. 1 (a), an annular light transmitting portion 3 and a recording film 4 are formed on the signal surface of a disk-shaped transparent substrate 2 having a central hole 1 by vapor deposition, sputtering, or the like.

Next, as shown in FIG. 1 (b), the center hole 1 is passed through the centering shaft 5 with the substrate 2 with the recording film 4 facing upward, and placed on a high flatness turntable 6. Thereafter, the liquid high-curing adhesive 7 is applied concentrically by the application nozzle 13 while rotating the turntable 6.

Next, as shown in FIG.
Is superimposed on the substrate 2, and furthermore, a high flatness pressing plate having a light transmitting hole 9 in an inner peripheral portion of the light transmitting portion 3 of the substrate 2.
The pressure-sensitive adhesive 10 is used to apply pressure from above the protective substrate 8 to spread the adhesive 7, and at the same time, turn on the light-emitting lamp 11 installed above the pressure plate 10, so that the light-transmitting holes 9 of the pressure plate 10 The protective substrate 8 is irradiated with light.

For this reason, the adhesive that has spread to the portion corresponding to the light-transmitting hole 9 that is pressurized is instantaneously cured because light transmitted through the protective substrate 8 shines, and spreads in the direction of the central hole 1. Is regulated.

Since the adhesive is light-cured instantaneously, it may be irradiated with light while confirming that the adhesive has spread to the central part visually or by a sensor, or empirically applying a certain pressing force to the pressing plate. Or pressurize with a certain stroke length,
Light irradiation may be performed.

Then, at the stage of light irradiation at the center, the distance between the two substrates is determined.

Next, as shown in FIG. 1 (d), the spread of the adhesive 7 in the direction of the center hole 1 is restricted, but the other substrate 2
Since the pressure plate is spread over the entire surface of the
10 is removed, and light is applied to the entire surface of the protective substrate 8 to cure the uncured portion of the adhesive 7.

When the optical disk is manufactured as described above, the bonding can be performed without protruding the adhesive 7 from the center hole 1 of the substrate 2.

In the present invention, the clay of the adhesive is preferably about 1200 cps. The thickness of the adhesive layer is about 100 after curing.
The average thickness is preferably about μm, and it has an allowable width of 20 to 30 μm.

Next, another embodiment of the present invention will be described. FIGS. 2 (a) to 2 (e) show a second embodiment of the method of manufacturing an optical disk according to the present invention, and are a bonding process diagram of a double-sided recording / reproducing optical disk having a full-contact structure.

In this embodiment, the two substrates 2, 2 'are both recording films 4,
Since the recording film 4 'is formed and the recording films 4 and 4' do not transmit light, a difference between the first embodiment and the first embodiment is in that a light / heat combined curing adhesive 7 is used as an adhesive used for bonding. .

That is, as shown in FIGS. 2 (a) to 2 (c), by bonding the substrate 2 and the substrate 2 'in the same manner as in the first embodiment, first, the adhesive 7 on the inner peripheral portion is cured by light curing. After curing and regulating the spread of the adhesive in the direction of the center hole,
As shown in FIG. 2 (d), the adhesive 7 is heated for a required time in an oven 14 set at a temperature suitable for thermal curing of the adhesive 7, and the uncured portion of the adhesive is cured by thermal curing.

In this way, by using the curable adhesive 7 combined with light and heat, the adhesive 7 can be removed from the center hole 1 of the substrate 2.
It is possible to easily manufacture an optical disk capable of recording and reproducing data on both sides without protruding.

In the first and second embodiments, the case of manufacturing an optical disc having a full-contact structure has been described. However, two substrates having a recording film are placed inside each other so that the recording films face each other with a certain space. The same effect can be obtained for an optical disk having an air sandwich structure having a structure in which the circumference and the outer circumference are bonded via a spacer.

As the substrate used in the present invention, an acrylic resin, a polycarbonate resin, a hard reinforced glass, or the like, which is generally used conventionally and has excellent light transmission characteristics, can be used. In addition, as long as the adhesive does not attack the recording film 4, a commonly used acrylic resin type, epoxy resin type, ultraviolet curable adhesive, or ultraviolet / heat curable adhesive may be used. Although it is possible, it is necessary to use it in consideration of the light absorption characteristics of the material used as the substrate.
The reason for considering the light absorption characteristics of the substrate material is that if the substrate is made of acrylic resin, polycarbonate resin, hard tempered glass, etc., these materials will mostly absorb and not transmit ultraviolet light with a wavelength of 300 nm or less, It is desirable to use an adhesive having a photocuring reaction wavelength range of 300 to 400 nm as an adhesive used for bonding.

Further, the recording film 4 may be any film such as a TeOx-based or TbFeCo-based film as long as recording and reproduction can be performed by light such as a laser beam.

[Effects of the Invention] As described above, according to the present invention, it is possible to regulate the spread of the adhesive in the direction of the center hole of the inner peripheral portion at the time of bonding, and to protrude the adhesive from the end face of the center hole of the substrate. And two substrates can be bonded together. That is,
Since the adhesive is instantaneously cured by irradiating light while the adhesive is spreading, it is possible to prevent the adhesive from protruding from the end face of the center hole of the substrate.

And a high-precision center hole diameter formed during substrate manufacturing,
Also, an optical disc can be manufactured without deteriorating the amount of eccentricity between the center hole and the recording / reproducing guide groove, and it is not necessary to correct the center hole by post-processing such as cutting after bonding, thereby reducing man-hours and costs. it can. Further, since the adhesive that has protruded from the center hole adheres to the centering shaft for preventing displacement and can be prevented from being cured, it is easy to remove the substrate from the centering shaft after bonding, and Therefore, the productivity can be improved without having to clean and replace the centering shaft each time it is used.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, in which a single-sided recording / reproducing optical disk having only a single-sided contact structure is bonded, and FIG. 2 shows a second embodiment of the present invention. FIG. 4 is a bonding process diagram of an optical disk having a double-sided recording / reproducing structure. FIG. 3 is a bonding step diagram in a conventional optical disk manufacturing method. 1: Center hole 2: Substrate 3: Transmissive part 4: Recording film 5: Center ring axis 6: Turntable 7: Adhesive 8: Protective substrate 9: Light transmissive hole 10: Pressure plate 11: Light emitting lamp 12: Reflector plate 13: Application nozzle 14: Oven 15: Adhesive protrusion

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/26 G11B 7/24

Claims (2)

(57) [Claims] 1. A recording film is selectively provided on a portion of at least one of the two transparent substrates having a central hole at a central portion except for an inner peripheral portion of one principal surface of the transparent substrate. After forming an optically transparent portion on the recording film side of the substrate, an adhesive having photo-curing properties is applied, and then the other transparent substrate is superimposed. A pressure plate having a light-transmitting region through which light for curing the light is pressed from the main surface opposite to the recording film forming main surface of the transparent substrate on which the recording film is formed to spread the adhesive, and to the light-transmitting portion. By irradiating the light through the light-transmitting region, the adhesive spread to the portion corresponding to the light-transmitting portion is immediately light-cured, and then the other uncured portion of the adhesive is cured. A method of manufacturing an optical disc, characterized by: 2. The method for manufacturing an optical disk according to claim 1, wherein the adhesive having photo-curing properties is a curable resin combined with light and heat.