JP2001357564A - Method for manufacturing disk type recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a disk type recording medium with high reliability by adjusting the mechanical accuracy such as warpage of a disk medium after lamination in a good state when the disk medium is produced by laminating two disk type substrates. SOLUTION: The method includes a process of applying a UV-curing adhesive 2a on two disk substrates 11, 12, a process of irradiating each disk substrate coated with the UV-curing adhesive with UV rays, a process of laminating the two disk substrates and a process of measuring the mechanical accuracy such as the warpage angle and wobbling of surface acceleration of the laminated disk medium. In the irradiation process of UV rays, the cumulative UV dose on each disk substrate is adjusted based on the measurement result of the measuring process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a disk-shaped recording medium such as a DVD, and more particularly to a method for manufacturing a disk-shaped recording medium in which two disk-shaped substrates are bonded.

[0002]

2. Description of the Related Art Disc-shaped optical recording media such as DVDs (digita
l versatile disk) is manufactured by laminating two disc-shaped substrates, and for this lamination,
For example, JP-A-9-69239 and JP-A-11-32
As disclosed in Japanese Patent No. 8753, an ultraviolet-curable adhesive is applied (printed) to two disk-shaped substrates, irradiated with ultraviolet rays, and then bonded.

[0003] Japanese Patent Application Laid-Open No. 10-165885 discloses an ultraviolet curable adhesive applied (printed) to two disk-shaped substrates, bonded together, irradiated with ultraviolet light, and cured by ultraviolet irradiation. It is disclosed to comprise light means.

However, the two disc-shaped substrates to be bonded are very thin, each having a thickness of about 0.6 mm, and are slightly warped even when used alone. The warpage slightly changes depending on the lot of the resin, which is the material of the substrate, the mold, the stamper, the molding machine, the molding conditions, the film forming conditions, and the like at the time of production. A recording layer or the like is formed on such a disk-shaped substrate and bonding is performed. However, it has been difficult to control the degree of warpage of the bonded disks by a conventional method. The two disc-shaped substrates to be bonded may be the same type or different types of substrates, and there may be multiple types of disc-shaped recording media to be manufactured. This is because the degree of warpage varies depending on the mold, stamper, molding machine, molding conditions, film forming conditions, and the like, and it is difficult to control the warpage after bonding.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention relates to a method of manufacturing a disk-shaped medium by bonding two disk-shaped substrates together. An object of the present invention is to provide a method for manufacturing a disk-shaped recording medium with high reliability by properly adjusting mechanical accuracy such as warpage in the above.

[0006]

In order to achieve the above object, a method for manufacturing a disk-shaped recording medium according to the present invention comprises:
A method of manufacturing a disk-shaped recording medium by bonding two disk-shaped substrates, comprising: applying an ultraviolet-curable adhesive to the two disk-shaped substrates; and applying the ultraviolet-curable adhesive to the two disk-shaped substrates. Irradiating each of the disc-shaped substrates with ultraviolet light, bonding the two disc-shaped substrates, and measuring mechanical accuracy of the bonded disc-shaped media, such as a warp angle and a plane deflection acceleration. Wherein the integrated ultraviolet light amount for each of the disk-shaped substrates is adjusted in the ultraviolet irradiation step based on the measurement result of the measurement step.

According to this method for manufacturing a disk-shaped recording medium, the integrated amount of ultraviolet light for each disk-shaped substrate is adjusted in the ultraviolet irradiation step based on the measurement result of the mechanical accuracy in the measurement step. And the mechanical accuracy such as warpage after bonding can be adjusted. As a result, a highly reliable disk-shaped recording medium with good mechanical accuracy can be manufactured. Since the integrated ultraviolet light amount can be expressed by the following equation, the ultraviolet irradiation time and / or the intensity of the ultraviolet light can be changed to adjust the integrated ultraviolet light amount.

[0008] Integrated UV light quantity = UV intensity x UV irradiation time

In this case, in the ultraviolet irradiation step, the applied ultraviolet light amount is adjusted so that the integrated ultraviolet light amount for one disk-shaped substrate is different from the integrated ultraviolet light amount for the other disk-shaped substrate. The degree of curing of the adhesive can be controlled so as to be different, and the mechanical accuracy such as warpage of the disc-shaped recording medium after bonding can be adjusted well.

Further, the measuring step and the adjustment of the integrated ultraviolet light amount are performed each time the lot of the disk-shaped substrate changes, so that when the lot changes, the warpage or the like in the disk-shaped recording medium after the lamination is changed. The machine accuracy is adjusted well and there is no decrease in machine accuracy due to a change in lot. Note that a lot is a concept representing a specific amount of a material or a product manufactured under the same conditions.A lot of a substrate is determined by a mold, a stamper, a molding machine, molding conditions, film forming conditions, and a material. If at least one of the mold, the stamper, the molding machine, the molding conditions, the film forming conditions, and the material is different, a different lot is used.

The measuring step and the adjustment of the integrated ultraviolet light amount are performed each time the type of the disk-shaped recording medium to be manufactured is changed. The mechanical accuracy such as warpage of the disk-shaped recording medium is well adjusted, and there is no decrease in mechanical precision due to the change in the type of disk-shaped recording medium. The types of disk-shaped recording media include types of double-sided use and single-sided specification in addition to types such as read-only, write-once, and rewritable.

In addition, a plurality of types of disk-shaped recording media can be manufactured by laminating the disk-shaped substrates by the respective steps in the above-described manufacturing method. This makes it possible to manufacture a plurality of types of disk-shaped recording media in the same process, thereby simplifying the process and improving the productivity.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a manufacturing method according to an embodiment of the present invention, and is a diagram illustrating a process of bonding two disk-shaped substrates in a manufacturing process of a DVD (digital versatile disk) that is a disk-shaped optical recording medium. It is. FIG. 2 is a diagram conceptually showing a cross-sectional configuration of various DVDs formed by laminating two disk-shaped substrates each having a signal recording area on at least one side.

First, referring to FIG. 2, the cross-sectional structure of various DVDs which need to be bonded and to which the present invention can be applied will be described.
A read-only DVD-ROM (DVD1) shown in FIG.
0) is a method in which a reflective film 22 and a protective film 23 are formed on a disc-shaped substrate 21 made of polycarbonate having a thickness of 0.6 mm and having pits, and an opposite surface 25 is formed with an adhesive layer 24 interposed therebetween.
A disc-shaped substrate made of polycarbonate and having pits having a similar reflective film and protective film formed thereon and having pits attached thereto and recording on both sides is adopted.
In the DVD-ROM (DVD5), a 0.6 mm polycarbonate disk-shaped substrate 51 shown in FIG. 2D is attached to the opposite surface 25 of FIG. It has a single-sided specification. In this case, a 0.6 mm polycarbonate disk-shaped substrate 61 having a reflective film 62 and a protective film 63 shown in FIG. 2E formed on the opposite surface 25 of FIG. 2A as a dummy-side substrate. Accordingly, in the case of the single-sided specification, the adhesive layer cannot be seen through from the substrate on the opposite surface 25 side, so that the appearance is improved, which is preferable.

A write-once DVD-R which can be written once, as shown in FIG. 2 (b), comprises a 0.6 mm-thick polycarbonate disk-shaped substrate 31 and an organic dye film 32 in this order.
, A reflective film 33 and a protective film 34, and the adhesive layer 3
0.6 m having a similar layer configuration on the opposite face 36 through 5
a disk-shaped substrate made of polycarbonate
It is a double-sided specification with recording on both sides. Alternatively, in the same manner as described above, the disk-shaped substrate 51 of FIG. 2D is attached to the opposite surface 36 or the disk-shaped substrate 61 having the layer configuration of FIG.

A phase-change type such as a rewritable type DVD-RAM, DVD-RW, DVD + RW or the like shown in FIG. 2C is made of polycarbonate having a thickness of 0.6 mm on which a hard coat layer 40 is formed. Disk-shaped substrate 4
1, a dielectric layer 42, a recording film 43 for recording information, a dielectric layer 44, a reflective film 45, and a protective film 46 in this order.
And a 0.6 mm polycarbonate disk-shaped substrate having a similar layer configuration is attached to the opposite surface 48 via an adhesive layer 47, and recording is performed on both surfaces. Alternatively, as the one-sided specification, the opposite side 48
2 (d) or a disk-shaped substrate 61 having a layer configuration shown in FIG. 2 (e). The reason that there are a plurality of types of rewritable DVDs is because the application format is different.
RAM for computer, DVD-RW for consumer, DV
D + RW can be used for both, but the format is different.

As described above, DVDs have different layer configurations depending on the type, and have a double-sided specification and a single-sided specification, all of which are manufactured by bonding two disk-shaped substrates. The steps will be described with reference to FIG.

The two disk-shaped substrates 11 and 12 made of polycarbonate having a thickness of 0.6 mm shown in FIG.
As shown in (b), a container 2 containing an adhesive 2a made of a cationically polymerizable UV-curable resin is arranged on the upper portion of the roll 1, and the adhesive 2a is disc-shaped from the container 2 while the roll 1 rotates in the direction R. It is applied to the substrates 11 and 12. And
As shown in FIG. 2C, ultraviolet rays are irradiated from the ultraviolet light sources 4 and 5 to the disk-shaped substrates 11 and 12 on which the adhesive layers 11a and 12a are respectively formed.

Thereafter, the surfaces of the adhesive layers 11a and 12a are opposed to each other as shown in FIG.
As shown in FIG. 2 (e), the two disc-shaped substrates 11, 12 are put together and sandwiched between the disks 6, 7 and pressed to bond the two disc-shaped substrates 11, 12, as shown in FIG. A disk-shaped optical recording medium 13 such as a DVD is manufactured.
In this case, the adhesive layer 11 of the disk-shaped substrates 11 and 12
a and 12a constitute, for example, the respective adhesive layers 24, 35 and 47 in FIGS. 2 (a), 2 (b) and 2 (c). Note that FIG.
In the adhesive application step (b), application is performed using a roller, but application may be performed using a spin coater method or a screen printing method.

The surface deflection acceleration and warpage of a DVD which is a disk-shaped optical recording medium obtained by bonding two disk-shaped substrates as described above are measured. In order to manufacture DVDs having various forms as shown in FIG. 2, in the step of bonding disk-shaped substrates, bonding conditions suitable for each DVD are required. Furthermore, even when manufacturing only DVDs of the same type, the characteristics of the finished DVD may be degraded if they are bonded together under the same conditions because the disc-shaped substrate has variations in warpage between lots. Therefore, the D obtained by bonding the disc-shaped substrates
The surface deflection acceleration and warpage of the VD are measured, and a bonding condition of an integrated ultraviolet light amount by ultraviolet irradiation in which these measured values are within a certain value is obtained, and bonding is performed under these conditions.

In this embodiment, the adhesive layer 11a of the disk-shaped substrate 11 is used in the ultraviolet irradiation step shown in FIG.
By adjusting the integrated amount of ultraviolet light so that the ultraviolet light irradiation time for the DVD and the ultraviolet light irradiation time for the adhesive layer 12a of the disc-shaped substrate 12 are different, the bonding conditions are changed for each type of DVD as shown in FIG. The bonding conditions are changed each time the lot of the disk-shaped substrate changes. Thereby, the degree of curing of the ultraviolet curable adhesive on each of the disk-shaped substrates 11 and 12 at the time of bonding is different, and mechanical accuracy such as warpage of the disk-shaped recording medium after bonding can be satisfactorily adjusted. Therefore, even if the type of DVD to be manufactured changes as shown in FIG.
Even if the lot of the resin as the material of the disk-shaped substrate changes and the degree of warpage changes, a DVD with good mechanical accuracy and high reliability can be manufactured efficiently.

Also, since a plurality of types of disk-shaped recording media can be manufactured by bonding the disk-shaped substrates in the above-described steps, a plurality of types of disk-shaped recording media can be manufactured in the same process. Since there is no significant change, the process can be simplified and the productivity can be improved.

[0023]

Next, an embodiment manufactured by the manufacturing process shown in FIG. 1 will be described. Each condition is as follows.

(1) Disk-shaped optical recording medium used: rewritable DVD-RAM, single-sided specification

[0025] (2) layer structure: a polycarbonate disc-shaped substrate having a thickness of 0.6 mm, in order ZnS · Si0 ₂
/ GaN / GeSbTe / ZnS · SiO 2 / AlCr
After that, a protective film (radical polymerizable ultraviolet curable resin, for example, SD313 manufactured by Dainippon Ink) was formed.

(3) Dummy-side substrate: A reflection film (for example, A
1) and a protective film (radical polymerizable ultraviolet curable resin such as SD318 (manufactured by Dainippon Ink)).

(4) Adhesive: Cationic polymerizable ultraviolet-curable resin XNR5533 (manufactured by Chise Nagase)

(5) Screen cloth at the time of applying an adhesive by a screen printing method: mesh number 420 (material is nylon)

Each sample of DVD was prepared for 5 lots by changing the ultraviolet irradiation time (irradiation amount) under the above conditions, and the surface deflection acceleration and warpage angle were measured at a radius of 23 to 58 m.
m at 5 mm intervals. The lot was determined based on differences in the mold, stamper, molding machine, molding conditions, film forming conditions, and materials used during substrate production.

The measurement of the plane runout acceleration and the warpage angle was performed using a DVD mechanical property evaluation device LM1200 manufactured by Ono Sokki Co., Ltd. Regarding the surface runout acceleration, the focus and tracking servo are applied to the guide groove of the DVD, the movement of the objective lens that traces the guide groove is measured, and the amount of vertical displacement at an arbitrary measurement point (for example, 256 points) in the circumference is measured. Was differentiated twice with respect to time to measure the circumferential runout acceleration in the circumferential direction. For warpage, φ1mm
Was irradiated onto the reflecting surface of the DVD, and the return angle of the reflected light was measured.

FIG. 3 is a graph showing the measurement results of samples prepared by changing the irradiation time of the ultraviolet rays to the adhesive layer of each disk-shaped substrate in the irradiation step of ultraviolet rays in FIG. . The horizontal axis represents the time of UV irradiation of the adhesive layer on both disc-shaped substrates. FIG. 3A shows the warpage angle in the radial direction, FIG. 3B shows the warpage angle in the circumferential direction, and FIG.
(C) shows the measurement results of the plane runout acceleration. In each graph, the worst value among the measured values is plotted.

As can be seen from FIG. 3A, the warp angle in the radial direction tends to deviate from the standard value (0.7 degrees or less) when the ultraviolet irradiation time is short, but falls within the standard when the ultraviolet irradiation time is long. As shown in FIG. 3B, a similar tendency is observed for the warp angle in the circumferential direction (the standard value is 0.3 degrees or less). However, as shown in FIG. 3C, when the irradiation time is long, the surface deflection acceleration exceeds the reference value (8 m / s ² ) for tracking the focus of the optical head of the apparatus. For example, the irradiation time is 1.5 seconds (integrated amount of ultraviolet light = about 1100 mJ /
cm ² ), both the radial and circumferential warpage angles are within the standard values, but the surface runout acceleration may or may not be within the specification depending on the lot. Would.

From the above measurement results of FIG.
It can be seen that, even in the case of producing a VD, it is necessary to adjust the ultraviolet irradiation time in the disk-like substrate bonding step every time the lot changes.

Next, for a DVD having the same specifications as in FIG. 3, the UV irradiation time of the film forming substrate (substrate on which the recording film is provided) is set to a constant 1.5 seconds, and the integrated UV light amount is about 1.1.
The same measurement was performed on five lots of samples manufactured by changing the ultraviolet irradiation time on the dummy-side substrate side to 00 mJ / cm ² . The measurement results are shown in FIG. 4, where the horizontal axis represents the ultraviolet irradiation time on the dummy side substrate side, FIG. 4 (a) is the radial warp angle, FIG. 4 (b) is the circumferential warp angle, and FIG. 4
(C) is a measurement result of the plane runout acceleration. In each graph, the worst value among the measured values is plotted.

As can be seen from the results shown in FIGS. 4A to 4C, when the time of irradiating the dummy substrate with ultraviolet light is 1.0 second (integrated amount of ultraviolet light = about 730 mJ / cm ² ), warpage in the radial direction is caused. Angle, circumferential warp angle and surface runout acceleration,
The results within the specification were obtained for all lots.

As described above, by freely adjusting the irradiation time of the ultraviolet light to each disk-shaped substrate, even if the lot of the resin material of the disk-shaped substrate changes, a disk-shaped optical recording medium such as a DVD of higher quality can be obtained. Can be manufactured stably.

Further, if the type of the disk-shaped optical recording medium changes, the values of the warp angle and the surface deflection acceleration also change.
Not only when the lot of resin material changes, but also
Even when the type of VD is switched, appropriate adjustment of the ultraviolet irradiation time is effective by such measurement.

As described above, the present invention has been described with reference to the embodiment and the examples. However, the present invention is not limited to these, and various modifications can be made within the technical idea of the present invention. . For example, DVD as a disc-shaped recording medium
-Although the description has been given by taking the single-sided specification of the RAM as an example, double-sided use may be used, and other types of DV as shown in FIG.
D, and of course, other disk-shaped recording media manufactured by laminating two disk-shaped substrates.

In the embodiment, the ultraviolet irradiation time for the ultraviolet-curable adhesive is changed. However, by changing the ultraviolet light intensity, or by changing both the irradiation time and the intensity, the integrated ultraviolet light amount is adjusted. It may be.

[0040]

According to the present invention, when two disk-shaped substrates are bonded together to produce a disk-shaped medium, the mechanical accuracy such as warpage of the bonded disk-shaped medium is adjusted well, and reliability is improved. It is possible to provide a method for manufacturing a disk-shaped recording medium having high performance.

[Brief description of the drawings]

FIG. 1 is a view schematically showing respective bonding steps (a) to (e) of two disk-shaped substrates according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view conceptually showing each cross-sectional configuration (a) to (c) for each type of DVD as a disc-shaped recording medium, and a cross-section showing each cross-sectional configuration (d) and (e) of a dummy substrate. FIG.

FIG. 3 is a graph showing measurement results of samples prepared by changing the irradiation time of the ultraviolet ray to the adhesive layer of each disk-shaped substrate in the irradiation step of ultraviolet light in FIG. FIG. 7 is a diagram showing measurement results of a warp angle (a), a circumferential warp angle (b), and a plane runout acceleration (c), respectively.

FIG. 4 is a graph showing measurement results of a sample manufactured by changing the ultraviolet irradiation time on the dummy-side substrate side while keeping the ultraviolet irradiation time on the film-forming substrate (the substrate on which the recording film is provided) constant in this example. FIG. 3 is a diagram showing measurement results of a radial warpage angle (a), a circumferential warpage angle (b), and a plane runout acceleration (c).

[Explanation of symbols]

 11, 12 disk-shaped substrate 11a, 12a adhesive layer 13 disk-shaped recording medium

Claims (5)

[Claims] 1. A method of manufacturing a disk-shaped recording medium by bonding two disk-shaped substrates together, comprising: applying an ultraviolet-curable adhesive to the two disk-shaped substrates; Irradiating each disk-shaped substrate with the mold adhesive applied thereto with ultraviolet light, bonding the two disk-shaped substrates, and measuring mechanical accuracy of the bonded disk-shaped media; A method of manufacturing a disk-shaped recording medium, comprising: adjusting an integrated amount of ultraviolet light for each of the disk-shaped substrates based on a measurement result of the measuring step in the ultraviolet irradiation step. 2. The method according to claim 1, wherein in the step of irradiating the ultraviolet light, the integrated ultraviolet light quantity is adjusted so that the integrated ultraviolet light quantity for one disk-shaped substrate is different from the integrated ultraviolet light quantity for the other disk-shaped substrate. 2. The method for producing a disk-shaped recording medium according to item 1. 3. The method for manufacturing a disk-shaped recording medium according to claim 1, wherein the measuring step and the adjustment of the integrated ultraviolet light amount are performed each time the lot of the disk-shaped substrate changes. 4. The disc-shaped recording medium according to claim 1, wherein the measuring step and the adjustment of the integrated ultraviolet light amount are performed each time the type of disc-shaped recording medium to be manufactured changes. Manufacturing method. 5. A disk-shaped recording method comprising: manufacturing a plurality of types of disk-shaped recording media by bonding the disk-shaped substrates by the respective steps in the manufacturing method according to claim 1, 2, 3, or 4. The method of manufacturing the medium.