JPH02308442A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To prevent the generation of local stresses at the time of sticking and to obviate the generation of the abnormality in the double refractions of a disk after sticking by forming injection-molded transparent substrates to the prescribed sectional shape of the stuck surfaces. CONSTITUTION:The respective sticking sections of the injection-molded transparent polycarbonate substrate 1 and the similarly molded transparent flat substrate 2 are formed to the projecting shape of the central part lower in the central part than recording regions. Laminated recording films 10 consisting of a dielectric film, magneto-optical recording film, dielectric film, reflecting film, etc., are provided on this substrate 1 and a dielectric film 11 is provided on the substrate 2. There are no parts projecting from the inner peripheral surface near the part in the 2nd gate of the inner peripheral part and the backward warpage on the inner peripheral surface around this part does not arise at the time of adhering the substrates 1, 2 if such substrates are adhered by an adhesive agent 12 in tight contact therewith. The generation of the local stresses at the time of the sticking is obviated and the abnormality in the double refractions is obviated. The degradation in an error rate is prevented and the optical recording medium enhanced in bumping accuracy and durability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing an optical recording medium for optical recording or reproduction.

[Prior Art] In recent years, research on optical recording media has been active and has progressed to the level of practical use. Therefore, the manufacturing method of the prior art is shown in FIG. 4 and will be described in detail. FIG. 4 is a cross-sectional view of the substrate in the manufacturing process of the optical recording medium.

As shown in Figure 4a, a PC board (group board 14) with at least a guide groove or various information signals is molded from polycarbonate by injection molding and has a thickness of 1.2 mm, an inner diameter of 15 mm, and an outer diameter of 130 mm. Molded by injection molding method, thickness 1.2mm, inner diameter φ
A flat substrate 15 with a diameter of 15 mm and an outer diameter of 130 mm is used. Here, the cross-sectional shape of the substrate was not clearly controlled.

In addition, there is a second game (17) on the innermost circumference of the recording area on the bonding surface.
(There is a presser mark on the inner periphery of the stamper).

As shown in FIG. 4B, after the substrate gas has been vented, a laminated film 10 of a dielectric film, a magneto-optical recording film (MO), a dielectric film, and a reflective film is formed on the group substrate 14 by sputtering. After the substrate gas was vented, a dielectric film 11 was formed on the flat substrate 15 by sputtering.

After that, as shown in Fig. 4C, the group substrate 14 and the flat substrate 1 are bonded together using the adhesive 12, which is an ultraviolet curing resin, in a vacuum.
Paste 5 together.

FIG. 4d shows a prior art disk 16 manufactured by irradiating ultraviolet light to cure the adhesive.

Furthermore, as shown in FIG. 4e, the hub 13 was attached to the disk 16 using an ultrasonic welding hub bonder.

[Problems to be Solved by the Invention] However, when manufacturing as shown in FIG. 3 using the above-mentioned conventional technology, depending on the cross-sectional shape of the bonding surface of the substrate before bonding,
Abnormal compressive stress occurs at the inner periphery of the recording area of the substrate.

This caused problems such as worsening of the birefringence of the substrate and protrusion of the center of the substrate toward the opposite side of the bonding surface.

In other words, the cross-sectional shape of the bonding surface of the substrates before bonding, such as the group substrate 14 and flat substrate 15 in FIG. If it is high, the white part on the inner periphery will be hit first when pasting.

The outer peripheries of the substrates are brought together by the surface tension of the adhesive, and the center of the substrates is raised on the opposite side of the bonding surface using the convex portion of the inner periphery as a fulcrum. Therefore, compressive stress is generated in the inner circumferential portion of the recording area, which serves as a fulcrum, worsening birefringence and worsening the error rate. Furthermore, since the center of the board is raised, it is difficult to attach the hub, and accuracy deteriorates.

Furthermore, since the surface tension of the adhesive is used to correct the warpage of the substrate, stress is constantly generated that tends to cause the adhesive to peel off after the adhesive has hardened, resulting in poor durability.

The present invention is intended to solve these problems, and its purpose is to eliminate the occurrence of birefringence abnormalities in disks after bonding, prevent deterioration of the error rate, improve hub attachment accuracy, and improve durability. This is where you can measure your improvement.

[Means for Solving the Problems] In a method for producing a bonded bonded optical recording medium having at least an optical recording layer and a protective layer on one side of a transparent resin substrate, bonding of transparent resin substrates molded by an injection molding method is provided. The cross-sectional shape of the surface is characterized in that the center of the substrate is lower than the recording area.

[Function] According to the above structure of the present invention, in a substrate molded by injection molding, it is specified that the inner periphery is lower than the second gate with respect to the outer periphery and the recording area.

The cross-sectional shape of the bonded surface of transparent resin substrates molded by injection molding is uneven, with the inner periphery being higher or lower than the second gate with respect to the outer periphery and recording area, and the shape of the transparent resin substrate after film formation. The cross-sectional shape of the bonded surfaces changes each time.

If the cross-sectional shape of the bonded surface of a transparent resin substrate molded by injection molding is such that the inner circumference is higher than the second gate with respect to the outer circumference or the recording area, the amount of substrate warpage is not due to the warpage of the recording area. The tangent between the inner peripheral portion higher than the second gate and the outer peripheral portion of the substrate becomes the amount of warpage, which has a positive tendency. Then, as a result of bonding, the convex portion at the center of the substrate hits first. Furthermore, since the outer peripheries of the substrates are brought together by the surface tension of the adhesive, the center of the substrate rises around the protrusion at the center of the substrate as a fulcrum. Therefore, it is necessary to specify the cross-sectional shape of the bonding surface of the transparent resin substrate before film formation.

In other words, when bonding, according to the above structure of the present invention, unreasonable stress is not locally applied to the substrate, eliminating the occurrence of birefringence abnormality in the disk after bonding, preventing deterioration of the error rate, and preventing hub attachment. It is possible to measure improvements in accuracy and durability.

[Example 1] Example 1 of the specific field of application of the present invention is a case where the cross-sectional shape of the bonded surfaces of transparent resin substrates for both the group plate and the flat plate is such that the center of the substrate is convex from the recording area.

The manufacturing method of Example 1 of the present invention will be described in detail in the manufacturing process of a magneto-optical recording medium in the manufacturing process of a magneto-optical recording medium, with reference to an example shown in FIG. FIG. 1 is a sectional view of a substrate in the manufacturing process of a magneto-optical recording medium.

As shown in Fig. 1 a, a PC board (group board 1) with at least a guide groove or various information signals is used, and the thickness is 1.2 mm, the inner diameter is 15 mm, and the outer diameter is 130 mm. Molded by injection molding method, thickness 1.2mmt, inner diameter φ1
A flat substrate 2 with a diameter of 5 mm and an outer diameter of 130 mm is used.

The cross-sectional shape of the bonded surface of transparent resin substrates molded by injection molding is such that the center of the substrate is 0 to 0.2 from the recording area.
It is better to lower it by 0.1 mm, preferably by 0.1 mm. In other words, the group substrate 1 and the flat substrate 2 have a stylus-type surface roughness meter (Talysurf) that shows that the inner circumference is lower than the second gate with respect to the outer circumference and recording area in the cross-sectional shape of the bonded surface of the transparent resin substrate. confirm. In the method of optically measuring the warp angle as a non-contact method, the group substrate 1 has an average of 100°5m.
rad and flat board 2 is +1. This is Omrad. (
The minus sign is concave with the film forming side facing up against the substrate. ) After the substrate gas is vented as shown in FIG. 1B, a laminated film lO of a dielectric film, a magneto-optical recording film (MO), a dielectric film, a reflective film, etc. is formed on the group substrate 1 by sputtering. After the substrate gas was vented, a dielectric film 11 was formed on the flat substrate 2 by sputtering.

After considering the original warpage and warpage direction of the film formed here, as well as the amount and direction of warpage due to the time the substrate is left in the atmosphere after film formation, we Confirm with a stylus type surface roughness meter (Talysurf) that the inner circumference is lower than the second gate with respect to the outer circumference and recording area. In the method of optically measuring the warp angle as a non-contact method, the group substrate 1 has an average of -7.0 to +2. Omr
up to ad, preferably less than +1.0 mrad. The flat substrate 2 has an average of −7.0 to +2° Omrad, preferably less than +1.0 mrad. (The minus side is concave with the film forming side facing up to the substrate.) Then, as shown in C in Figure 1, group substrate 1 and flat substrate 2 are bonded using adhesive 12, which is an ultraviolet curing resin, in a vacuum. Pasted together.

1d in FIG. 1 is a disk 3 of Example 1 of the present invention manufactured by irradiating ultraviolet rays to cure the adhesive.

Further, as shown in FIG. 1(e), the hub 13 was attached to the disk 3 using an ultrasonic welding hub bonder.

[Example 2] In another example 2 of the present invention, the group substrate has a cross-sectional shape of the bonded surface of transparent resin substrates, and the center portion of the substrate is concave from the recording area. On the other hand, in the flat substrate 5, the cross-sectional shape of the bonded surface of the transparent resin substrate is the same as the conventional one (convex) at the center of the substrate from the recording area.

The manufacturing method of Example 2 of the present invention will be described in detail in the manufacturing process of a magneto-optical recording medium in the manufacturing process of a magneto-optical recording medium, with reference to an example shown in FIG. FIG. 2 is a sectional view of a substrate in the manufacturing process of a magneto-optical recording medium.

As shown in Fig. 2 a, a PC board (group board 4) with at least a guide groove or various information signals is used, which is made of polycarbonate by injection molding and has a thickness of 1.2 mm, an inner diameter of 15 mm, and an outer diameter of 130 mm. Molded by injection molding method, thickness 1.2mm, inner diameter φ
A flat substrate 5 with a diameter of 15 mm and an outer diameter of 130 mm is used.

Here, in the cross-sectional shape of the bonded surface of the transparent resin substrate molded by injection molding, the center of the substrate is 0 to 0.2 mm lower than the recording area, preferably 0.1 mm lower. That is, in the group substrate 4, it is confirmed using a stylus type surface roughness meter (Talysurf) that the inner circumference is lower than the second gate with respect to the outer circumference and the recording area in the cross-sectional shape of the bonded surface of the transparent resin substrate. In the non-contact method of optically measuring the warp angle, the average value is -1, Omrad. (The minus side is concave with the film forming side facing up against the substrate.) On the other hand, the flat substrate 5
This is a case where the inner periphery is lower than the second gate with respect to the outer periphery or the recording area in the cross-sectional shape of the bonded surface of the transparent resin substrate, as in the conventional case.

In the non-contact method of optically measuring the warp angle,
The average is +0.5 mrad. (The plus sign is convex with the film forming side facing up to the substrate.) After the substrate gas is vented as shown in Fig. 2b, the group substrate 4 is covered with a dielectric film, a magneto-optical recording film (MO), a dielectric A laminated film 10 including a body film, a reflective film, etc. is formed by sputtering. After the substrate gas was vented, a dielectric film 11 was formed on the flat substrate 5 by sputtering.

Here, after taking into account the amount and direction of warpage that the formed film itself inherently has, and the amount and direction of warpage that the substrate will experience after being left in the atmosphere after film formation, Confirm with a stylus type surface roughness meter (Talisurf) that the inner circumference is lower than the second gate with respect to the outer circumference and the recording area in the cross-sectional shape. In the method of optically measuring the warp angle as a non-contact method, the group substrate 4 has an average of -7.0 to +1. Om
up to rad, preferably -0.5 mrad or less.

The flat substrate 2 has an average temperature of 0 to +5. Up to Omrad, preferably less than +0.5mrad. (The minus side is concave with the film forming side facing up to the substrate.) Then, as shown in Fig. 2C, the group substrate 4 and the flat substrate 5 are bonded together using the adhesive 12, which is an ultraviolet curing resin, in a vacuum. Pasted together.

FIG. 2d shows a disk 6 of Example 2 of the present invention manufactured by irradiating ultraviolet rays to cure the adhesive.

Further, as shown in FIG. 2e, the hub 13 was attached to the disk 6 using an ultrasonic welding hub bonder.

The amount of warpage before bonding in Example 2 is exactly the same even if the amount of warpage between the group substrate and the flat substrate is reversed. The effect is the same if the sum of the warpage amounts of the group substrate and the flat substrate is between +2.0 and -7.0 mrad, preferably -1.0 mrad.

- [Embodiment 3] In Embodiment 3 of a specific field of application of the present invention, the cross-sectional shape of the bonded surfaces of the transparent resin substrates for both the group plate and the flat plate is such that the center of the substrate is concave from the recording area.

The manufacturing method of Example 3 of the present invention will be described in detail in the manufacturing process of a magneto-optical recording medium in the manufacturing process of a magneto-optical recording medium, with reference to an example shown in FIG. FIG. 3 is a cross-sectional view of the substrate in the manufacturing process of the magneto-optical recording medium.

As shown in Fig. 3a, a PC board (group board 7) with at least a guide groove or various information signals, molded from polycarbonate with a thickness of 1.2 mm, an inner diameter of 15 mm, and an outer diameter of 130 mm, is used, as shown in Figure 3a. A flat substrate 8 having a thickness of 1.2 mm, an inner diameter of 15 mm, and an outer diameter of 130 mm is also molded by injection molding.

Here, in the cross-sectional shape of the bonded surface of the transparent resin substrate molded by injection molding, it is preferable that the center of the substrate is lower than the recording area by 0.2 mm from O, preferably by 0.001 mm. In other words, the group substrate 7 and the flat substrate 8 are tested using a stylus-type surface roughness meter to determine that the inner periphery is lower than the second gate with respect to the outer periphery or recording area in the cross-sectional shape of the bonded surface of the transparent resin substrate.
Check with Talysurf). In the method of measuring the warp angle optically as a non-contact method, the group substrate 7 has an average of -1
, 5 mrad, and the flat substrate 8 is -1, Omrad. (The minus side is concave with the film formation side facing up to the substrate.) After the substrate gas is vented as shown in Fig. 3b, the group substrate 7 has a dielectric film, a magneto-optical recording film (MO), and a dielectric film. A laminated film 10 such as a film, a reflective film, etc. is formed by sputtering. After the substrate gas was vented, a dielectric film 11 was formed on the flat substrate 8 by sputtering.

After taking into consideration the amount and direction of warpage that the film formed itself originally has, and the amount and direction of warp that the substrate will warp for after being left in the atmosphere after film formation, the cross section of the bonded surface of the transparent resin substrate is Confirm with a stylus type surface roughness meter (Talysurf) that the inner circumference is lower than the second gate with respect to the outer circumference and recording area. In the method of optically measuring the warp angle as a non-contact method, the group substrate 7 has an average of -7.0 to +2. Omr
Up to ad, +1 if possible. Up to Omrad is good. The flat substrate 8 is on average from -7.0 to +2° Omrad, preferably +1. Up to Omrad is good. (The minus side is concave with the film forming side facing up to the substrate.) Then, as shown in Fig. 3C, the group substrate 7 and the flat substrate 8 are bonded together using the adhesive 12, which is an ultraviolet curing resin, in a vacuum. Pasted together.

FIG. 3d shows a disk 9 of Example 3 of the present invention manufactured by irradiating ultraviolet rays to cure the adhesive.

Thereafter, as shown in FIG. 3e, the hub 13 was attached to the disk 9 using an ultrasonic welding hub bonder.

However, in the embodiment of the present invention, the warp angle is optically measured as a non-contact method, and it is said that the group board 1 and flat board 2 can be up to +2.0 mrad, but a slight positive warp may be caused by the adhesive. It can be absorbed by its thickness.

Although the present invention uses a substrate with an outer diameter of 130 mm, the present invention can also be applied to a substrate with an outer diameter of 120 mm or 90 mm.

Furthermore, although this example does not specifically describe the double-sided bonded media, the part that is bonded to the other PC board in each example is just the other medium, and the manufacturing method is basically the same. be.

Furthermore, although we used an adhesive that is an ultraviolet curable resin in a vacuum to bond the substrates together, any type of adhesive, such as epoxy, hot melt, or adhesive sheet, will have the same effect even if they are bonded together in the air. be.

, 1 Although the present invention uses a polycarbonate (PC) substrate, the present invention can also be applied to other substrates such as epoxy, which has a moisture absorption rate comparable to that of a PC substrate.

[Effects of the Invention] As described above, according to the present explanation, the local stress caused by bonding is eliminated and the occurrence of abnormal birefringence is eliminated, so the error rate is improved and the abnormal protrusion at the center of the substrate is reduced. By not having a hub, accuracy can be improved when using a hub.

Furthermore, because the surface tension of the adhesive does not correct the warpage of the substrate by force, the adhesive does not generate any stress that would cause it to peel off after it hardens, thereby improving durability.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a substrate in the manufacturing process of an optical recording medium in Example 1 of the present invention. FIG. 2 is a cross-sectional view of a substrate in the manufacturing process of an optical recording medium in Example 2 of the present invention. FIG. 3 is a cross-sectional view of a substrate in the manufacturing process of an optical recording medium in Example 2 of the present invention. FIG. 4 is a sectional view of a substrate in the manufacturing process of a conventional optical recording medium. 1... Group substrate of Example 1 of the present invention 2... Flat substrate of Example 1 of the present invention 3... Example 1 of the present invention
Disk 4... Group substrate 5 of Embodiment 2 of the present invention... Flat substrate 6 of Embodiment 2 of the present invention... Embodiment 2 of the present invention
Disk 7... Group substrate 8 of Embodiment 3 of the present invention... Flat substrate 9 of Embodiment 3 of the present invention... Embodiment 3 of the present invention
Disk 10...Laminated film (dielectric film, magneto-optical recording film (Mo) dielectric film, reflective film, etc.) 11...Dielectric film 12...Adhesive 13...Hub 14...Group substrate of conventional technology 15.Flat substrate of the prior art 16.Disc 17 of the prior art.There is a second gate (stamper inner periphery pressing trace). Applicant: Seiko Epson Co., Ltd. Representative Patent Attorney Kizobe Suzuki (and 1 other person) Figure 1

Claims (1)

[Claims] In a method for producing a bonded bonded optical recording medium having at least an optical recording layer and a protective layer on one side of a transparent resin substrate, the cross-sectional shape of the bonded surface of the transparent resin substrate molded by injection molding is A method for manufacturing an optical recording medium, characterized in that the center of the substrate is low.