JPH02308443A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To obtain such a recording medium which is not locally applied with undue stresses by controlling the sectional shape, camber direction and camber quantity in the central part of the sticking surfaces of substrates, the composite stress and direction of laminated films, etc. CONSTITUTION:The sectional shapes of the sticking surfaces of the transparent groove substrate 1 molded of polycarbonate and the similar transparent flat substrate 2 are formed to the shape at the sticking surfaces which is recessed in the central part than recording regions, by which the camber direction and camber quantity of the sticking surfaces are controlled. The synthetic force and direction of the dielectric film, magneto-optical recording film, dielectric film, reflecting film, etc., of the substrate 1 are so controlled as not to affect the camber direction of the substrate 1. The substrates 2 having the dielectric films 8 and 1 are adhered via a UV adhesive resin 9 in a vacuum and since there are on fulcra, etc., to invert the camber, the local application of the undue stresses on the substrates of the disk 3 formed by the adhesion does not arise. There is, therefore, no generation of the abnormality in double refractions and the degradation in the error rate is prevented; in addition, the bumping accuracy and durability are enhanced.

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 will be described in detail with reference to FIG. FIG. 3 is a cross-sectional view of the substrate in the manufacturing process of the optical recording medium.

As shown in Fig. 3a, a PC board (group board 11) with at least a guide groove or various information signals, with a thickness of 1.2 mm, an inner diameter of 15 mm, and an outer diameter of 130 mm, is made of polycarbonate by injection molding. Thickness 1. Molded by injection molding method. 2 mm t,
A flat substrate 12 with an inner diameter of 15 mm and an outer diameter of 130 mm is used.

A second gate 14 is provided at 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. 3B, after the substrate gas has been vented, a laminated film 7 consisting of a dielectric film, an electric film, a magneto-optical recording film (MO), a dielectric film, and a reflective film is formed on the group substrate 11 by sputtering. After the substrate gas was vented, a dielectric film 8 was formed on the flat substrate 12 by sputtering. Here, the amount of warpage of the substrate was not clearly controlled.

After that, as shown in FIG. 3C, the group substrate 11 and the flat substrate 12 are bonded together using adhesive 9, which is an ultraviolet curing resin, in a vacuum.
Paste them together.

FIG. 3d shows a prior art disk 13 manufactured by irradiating ultraviolet light to cure the adhesive.

Further, as shown in FIG. 3e, the hub 10 was attached to the disk 13 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, the cross-sectional shape of the bonded surface of the substrate before bonding changes depending on the warp direction and amount of warp, and the record of the board changes. Abnormal compressive stress occurs at the inner periphery of the area.

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 11 and flat substrate 12 in a of FIG. If the inner circumferential portion of the recording area is higher than the recording area, the inner circumferential portion of the recording area will hit first when bonding. Then, the outer peripheral parts of the substrates are brought together by the surface tension of the adhesive, and as a result, the center of the substrate is raised on the opposite side of the bonding surface using the convex part of the inner peripheral part of the recording area as a fulcrum. As a result, compressive stress is generated at the inner circumference of the recording area, which serves as a fulcrum, worsening birefringence.
And the error rate worsens. Furthermore, the central part of the board was raised, making it difficult to attach the hub and reducing accuracy.

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 a problem of 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] (1) The method for manufacturing an optical recording medium of the present invention is a method for manufacturing a contact bonded optical recording medium having at least an optical recording layer and a protective layer on one side of a transparent resin substrate. The method is characterized in that the bonding surfaces of the substrates before bonding and the cross-sectional shape of the center portion of the substrates are controlled.

(2) The method is characterized by controlling the direction and amount of warpage of the substrate before bonding.

(3) It is characterized by controlling the composite stress and direction of the combined laminated film of an optical recording layer and a protective layer or a reflective layer.

[Function] According to the above configuration of the present invention, it is specified that the center portion of the substrate before bonding is lower than the outer peripheral portion.

This is because the direction and amount of warpage of the substrate molded by injection molding is not constant, or due to the combined stress of the laminated film that combines the optical recording layer and the protective layer or reflective layer, the warpage of the medium after film formation may be caused by the plastic substrate. Since the sides expand and warp occurs, the cross-sectional shape of the bonded surface of the transparent resin substrate before film formation changes each time.

Therefore, it is necessary to specify the cross-sectional shape of the bonding surface of the transparent resin substrate before film formation. However, this depends on the amount and direction of warpage inherent to the substrate itself, the amount and direction of warpage inherent to the film itself, and the amount and direction of warpage due to the length of time the substrate is left in the atmosphere after film formation. In consideration of this, it is necessary to specify that the cross-sectional shape of the bonding surface of the transparent resin substrate is such that the center of the substrate is lower than the recording area.

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 concave 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. 1a, a PC board (group board 1) with various information signals is used, or a guide groove with a thickness of 1.2 mm, an inner diameter of 15 mm, and an outer diameter of 130 mm is molded by injection molding from polycarbonate. , a flat substrate 2 with a thickness of 1.2 mm, an inner diameter of 15 mm, and an outer diameter of 130 mm, also molded by the injection molding method.
Use.

Here, for group substrate 1 and flat substrate 2, the cross-sectional shape of the bonded surface of transparent resin substrates is determined by optically measuring the warp angle using a non-contact method, which shows that the center of the substrate is concave from the recording area. Check with.

The group substrate 1 has an average of -1.5 mrad and the flat substrate 2 has an average of -1.0 mrad. (The minus side is concave with the film forming side facing up with respect to the substrate.) After the substrate gas has been vented as shown in Fig. 1b, the group substrate 1 has a dielectric film, a magneto-optical recording film (MO), a dielectric A laminated film 7 such as a body film and a reflective film is formed by sputtering. After the substrate gas was vented, a dielectric film 8 was formed on the flat substrate 2 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 The shape indicates that the center of the substrate is more concave than the recording area.
Confirm by optically measuring the warp angle using a non-contact method. Group board l averaged -7.0 to +1.0mra
up to d, preferably -1.0 mrad. The flat substrate 2 has an average value of -7.0 to +1. Until omrad,
Preferably -1.0mrad. (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 9, 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 10 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 such that the center portion of the substrate is convex from the recording area as in the conventional case.

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. 2a, 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. Similarly 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 group substrate 4, it is confirmed that the cross-sectional shape of the bonded surface of the transparent resin substrates is concave at the center of the substrate from the recording area by optically measuring the warp angle using a non-contact method. Group substrate 1 has an average of -1.0 mrad. (The negative sign is concave with the film forming side facing up against the substrate.) On the other hand, in the flat substrate 5, the cross-sectional shape of the bonded surface of the transparent resin substrate is such that the center of the substrate is convex from the recording area as in the conventional case. This is the case. The average warp angle is +0°5 mrad using a non-contact method that optically measures the warp angle.
(The plus sign is convex with the film forming side facing up to the substrate.) After the substrate gas has been vented as shown in Fig. 2b, the group substrate 4 has a dielectric film, a magneto-optical recording film (MO), a dielectric A laminated film 7 such as a body film and a reflective film is formed by sputtering. After the substrate gas was vented, a dielectric aS film was formed on the flat substrate 5 by sputtering.

Here, the amount of warpage inherent in the formed film itself and -
Considering the direction of warpage and the amount and direction of warpage due to the time the board is left in the air after film formation, the cross-sectional shape of the bonded surface of the transparent resin substrate should be such that the center of the board is concave from the recording area. This is confirmed by optically measuring the warp angle using a non-contact method. Group board 1 averaged -7.0 to +1.0m
up to rad, preferably -0.5 mrad 0 Flat board 2 has an average of 0 to +5.0 mrad,
If possible, it is preferably +0.5 mrad or less. (Minus is
It is concave with the film formation side facing up against the substrate. ) Thereafter, as shown in FIG. 2C, the group substrate 4 and the flat substrate 5 were bonded together in a vacuum using an adhesive 9 made of ultraviolet curing resin.

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 10 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 warpage of the group substrate and the flat substrate are reversed. And the sum of the amount of warpage of the group board and the flat board is +2.0 to -7, Omrad, preferably -
The effect is the same if it is 1.0 mrad.

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 +1.0 mrad, but a slight positive warp may occur due to 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 substrates with an outer diameter of 120 mm or 90 mm.

Furthermore, although this embodiment does not specifically describe the double-sided bonded media, the part of each embodiment that is bonded to the other PC board becomes the other medium, and the control 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.

Although a polycarbonate (PC) substrate is used in the present invention, the present invention can also be applied to other substrates such as epoxy, which has a water absorption rate comparable to that of a PC board.

[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 eliminating it, the accuracy of the time when using a hub will be improved.

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 cross-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 sectional view of a substrate in the manufacturing process of a conventional optical recording medium. l...Group substrate 2 of Embodiment 1 of the present invention...Flat substrate 3 of Embodiment 1 of the present invention...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...Laminated film (dielectric film, magneto-optical recording film (MO) dielectric film, reflective film, etc.) 8...Dielectric film 9...Adhesive 10...Hub 11...Prior art Group board 12...Flat board 13 of the prior art...Disc 14 of the prior art...Second gate (stamper inner periphery pressing trace) and above

Claims (3)

[Claims] (1) In a method for manufacturing 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 bonded surface of the substrates before bonding and the cross-sectional shape of the center portion of the substrates are A method for manufacturing an optical recording medium, characterized by controlling. (2) The method for manufacturing an optical recording medium according to claim 1, further comprising controlling the direction and amount of warpage of the substrate before bonding. (3) The method for manufacturing an optical recording medium according to claim 1, characterized in that the combined stress and direction of the combined laminated film of the optical recording layer and the protective layer or the reflective layer are controlled.