Optical disc manufacturing method and optical disc

Abstract

The invention discloses an optical disc manufacturing method and an optical disc, and the optical disc manufacturing method comprises a manufacturing process of forming a forming substrate with a guide groove, and the manufacturing process comprises the following steps: arranging an original disc for transferring the guide groove to the forming substrate on the surface of a heat insulation layer of a forming substrate forming mold with the heat insulation layer; the heat insulation layer is arranged on a fixed die of a forming die of the forming substrate, the original disc is arranged on the heat insulation layer, and the temperature of the fixed die is set to be 107-114 DEG C; forming a molded substrate by a manufacturing method in which a polycarbonate molten resin is injected into the molded substrate molding mold, a movable side of the molded substrate molding mold is compressed, and a guide groove is transferred onto the injected polycarbonate molten resin; the forming substrate with the guide groove passes through the original disc and the heat insulation layer of the fixed mold, heat exchange cooling is carried out between the fixed mold and the movable side, and when the temperature of the forming substrate is reduced to 109-115 DEG C, the forming substrate is taken out of the mold. According to the optical disc manufactured by the optical disc manufacturing method disclosed by the invention, the difference between the maximum warping angle and the minimum warping angle in the radius direction can be ensured to be small, and the optical disc is ensured to have better read-write performance.

Description

Technical Field

[0001] The present invention relates to the technical field of optical disc manufacturing, and in particular to an optical disc manufacturing method and an optical disc. Background Art

[0002] Blu-ray discs are single-sided structures with a substrate thickness of 1.1 mm. Figure 1-a As shown in the figure, in order to achieve high capacity, the archiving optical disc (300GB / 500GB) has a substrate thickness reduced to less than 0.53mm and a single-sided 3-layer / double-sided 6-layer structure. Figure 1-b As shown, with the further increase in capacity, the 1TB archival optical disc adopts a single-sided 4-layer and double-sided 8-layer structure, and the spacing is narrowed from the original 225nm to less than 200nm.

[0003] As the thickness of the molding substrate becomes thinner, the rigidity decreases, and the pitch of the guide grooves becomes narrower, it is difficult to obtain the expected groove transfer performance from the original plate when molding the L0 substrate with a narrow pitch in the molding 0. The traditional molding technology requires increasing the mold temperature (4°C) for molding. As a result, the residual stress during substrate molding will increase, and since the substrate temperature drops sharply during mold opening and mold removal, the AC (Alternating Current) tilt of the substrate becomes larger, making it difficult to meet the specification requirements.

[0004] The AC tilt refers to the difference in angle between a portion with the largest warp (tilt) and a portion with the smallest warp in the radial direction of the optical disk.

[0005] In addition, as a change from Blu-ray Disc to Archive Disc, e.g. Figure 2-a The numerical aperture (NA) of a Blu-ray Disc (BD) is 0.85, while Figure 2-b The NA of the 1TB archival optical disc shown is 0.91, that is, the NA is increased from 0.85 to 0.91, which greatly increases the impact of COMA (COMAtic Aberration) aberration. When the optical disc is tilted relative to the optical axis of the incident light beam, the COMA aberration increases in proportion to the cube of the NA. Therefore, when the same tilt is generated, the 1TB optical disc will produce a larger COMA aberration.

[0006] The optical drive has a function to learn the optimum recording power to obtain the best performance to compensate for the reduction in the intensity of the focused beam. However, due to the COMA error (focus offset) caused by the AC tilt, the recording power is reduced and the performance is degraded.

[0007] like Figure 3Figure a shows the relationship between the signal quality index (Level Jitter) corresponding to the recording power when the optimal value of the recording power learning is normalized to 1. When the normalized power is 1, the signal quality is optimal. When the power shifts from the normalized power to a lower direction due to COMA reception error, the signal quality index deteriorates. The optical drive has the function of learning the recording power to compensate for the reduction in the intensity of the focused light beam caused by the variation in the film thickness of the optical disc and the inclination in the diameter direction. In order to compensate for the reduced intensity, the recording power is learned in a certain interval (Zone) in the radial direction, and the recording power can be corrected for each interval from the inner circumference to the outer circumference of the optical disc. However, if Figure 4 As shown, when an AC slope is generated (see Figure 5 ), COMA aberration will occur in one circle (one rotation) of the disc, and the intensity of the focused light beam will decrease. Figure 3 Figure b shows the playback signal waveform of a disc with a smaller AC tilt, and there is no significant change in the rotation of the disc 1. Figure 3 As shown in Figure c, when there is a large AC tilt, the amount of light collected by the recording power changes in a cycle of 1 rotation, and it is difficult to properly compensate for the recording power according to the change of 1 rotation, resulting in deterioration of the recording and playback performance. Therefore, in order to control the AC tilt of the optical disc that causes the deterioration of the writing and reading performance of the optical drive to a value below a certain value, a new AC tilt specification was introduced. Summary of the invention

[0008] The present invention proposes a method and device for manufacturing an optical disc in order to solve the above problems.

[0009] The technical means adopted by the present invention are as follows:

[0010] A method for manufacturing an optical disc, wherein the manufacturing process of forming a molded substrate with a guide groove comprises the following steps:

[0011] A master plate for transferring the guide grooves to the molding substrate is provided on a surface of a thermal insulation layer of a molding die for molding the molding substrate having a thermal insulation layer;

[0012] The heat-insulating layer is arranged on the fixed mold of the molding substrate molding die, the original disk is arranged on the heat-insulating layer, and the temperature of the fixed mold is set to 107°C to 114°C;

[0013] The molded substrate is formed by injecting a polycarbonate molten resin into a mold of the molded substrate, and a movable side of the mold of the molded substrate is compressed to form the molded substrate by a manufacturing method in which the guide groove is transferred to the injected polycarbonate molten resin;

[0014] The molded substrate with guide grooves passes through the original plate of the fixed mold and the insulation layer, and is cooled by heat exchange between the fixed mold and the movable side. When the temperature of the molded substrate drops to 109°C to 115°C, it is taken out of the mold.

[0015] Furthermore, the heat insulating layer can temporarily delay the heat exchange from the original plate to the fixed mold of the molding substrate molding mold.

[0016] Furthermore, the molding method of the molding substrate with the guide groove is controlled as follows:

[0017] The time for injecting the polycarbonate molten resin into the molding die of the molding substrate is 0.07 seconds to 0.17 seconds;

[0018] Due to the effect of the present invention, the time from the start of the molding cycle to the removal of the molded substrate with the guide groove from the molded substrate molding die is 3 to 5 seconds. If it is less than 3 seconds, significant warping (deformation) will occur due to insufficient cooling.

[0019] Furthermore, the heat insulating layer in the substrate forming mold is made of ceramics having a lower thermal conductivity than conventional metal materials.

[0020] Furthermore, the temperature of the polycarbonate molten resin during injection is 340° C. to 390° C.

[0021] Furthermore, the temperature when the polycarbonate molten resin is injected is 390° C., which can avoid deterioration of warpage and discoloration of the polycarbonate resin caused by insufficient cooling at 340° C. during the guide groove transfer.

[0022] Furthermore, the thickness of the molded substrate is 0.53 mm or less.

[0023] Furthermore, a pitch of the guide grooves is 200 nm or less.

[0024] Furthermore, it also includes forming four or more recording layers on the molded substrate with the guide groove for recording and playing information, and forming a resin layer for separating the recording layers to form a single-sided optical disc;

[0025] Then, the surfaces of the molded substrates of the two single-sided optical discs opposite to the surface having the guide groove are bonded to each other to form a double-sided optical disc.

[0026] A disc is formed by bonding two single-sided discs together, with 4 or more recording layers and 3 or more resin layers for separating the recording layers arranged on a molded substrate and one side thereof; the molded substrate of the single-sided disc is manufactured according to the disc manufacturing method disclosed in the present application.

[0027] Furthermore, the thickness of the molding substrate is 0.53 mm or less, and the spacing of the guide grooves is 200 nm or less.

[0028] Compared with the prior art, the optical disc manufacturing method disclosed in the present invention has the following beneficial effects: the present invention adopts a molding substrate molding mold with a heat insulating layer to manufacture a molding substrate of a single-sided optical disc, and the fixed mold of the molding substrate molding mold is maintained at a temperature of 107°C to 114°C during the manufacturing process. The temperature of the molding substrate with a guide groove is reduced to 109°C to 115°C when it is taken out of the mold, which can effectively reduce the residual stress in the molding process of the molding substrate, thereby reducing the AC tilt problem of the molding substrate, and thereby improving the read and write performance of the optical disc. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1-a This is a structural diagram of a traditional 500GB archive disc (AD);

[0030] Figure 1-b A structural diagram of an archiving optical disc disclosed in the present invention;

[0031] Figure 2-a is a schematic diagram of the numerical aperture of a conventional Blu-ray Disc (BD);

[0032] Figure 2-b A schematic diagram of the numerical aperture of the archiving optical disc disclosed in the present invention;

[0033] Figure 3 Figure 1 is the relationship between AC tilt and recording power learning, where Figure a shows the relationship between the signal quality index (Level Jitter) corresponding to the recording power when the optimal value of the recording power learning is normalized to 1; Figure b shows the playback signal waveform of a disc with a small AC tilt, and there is no large change within 1 rotation of the disc; Figure c shows that in the presence of a large AC tilt, the light concentration of the recording power changes with a cycle of 1 week;

[0034] Figure 4 When AC tilt is applied to the optical disc, COMA aberration will occur during one revolution of the optical disc, causing the intensity of the concentrated beam to decrease and the focus to shift.

[0035] Figure 5 Produces AC tilt for the disc;

[0036] Figure 6 The relationship between the fixed mold temperature and the groove transfer rate when forming a narrow guide groove with a track spacing by injection molding in the prior art;

[0037] Figure 7 is the relationship between the fixed mold temperature and the AC inclination;

[0038] Figure 8 It is a schematic diagram of the optical disc manufacturing process disclosed by the present invention;

[0039] Fig. 9Schematic diagram of the position between the molding substrate and the molding substrate molding mold, wherein Figure a is a molding substrate molding mold without a heat insulating layer; Figure b is a molding substrate molding mold with a heat insulating layer;

[0040] Fig.10 Schematic diagram of heat transfer between a molding substrate and a molding substrate molding mold, wherein Figure a is a molding substrate molding mold without a thermal insulation layer; Figure b is a molding substrate molding mold with a thermal insulation layer;

[0041] Fig.11 A schematic diagram showing temperature comparison during the transfer process between a molding substrate molding mold without a heat insulating layer and a molding substrate molding mold with a heat insulating layer;

[0042] Fig.12 It is a schematic diagram comparing the fixed mold temperature and the guide groove transfer rate in the prior art and the present invention;

[0043] Fig.13 It is a schematic diagram comparing the temperature of the fixed mold and the temperature of the molded substrate when it is taken out of the mold in the prior art and the present invention;

[0044] Fig.14 It is a schematic diagram comparing the relationship between the fixed mold temperature and the AC inclination in the prior art and the present invention. DETAILED DESCRIPTION

[0045] A method for manufacturing an optical disc, wherein the manufacturing process of forming a molded substrate with a guide groove comprises the following steps:

[0046] As a means of temporarily delaying heat exchange between the original disk and the fixed side of the optical disk substrate molding mold, a bottom plate for transferring the guide grooves to the molding substrate is provided on the thermal insulation layer of the optical disk substrate molding mold having a ceramic thermal insulation layer;

[0047] The heat-insulating layer is arranged on the fixed mold of the molding substrate molding die, the original disk is arranged on the heat-insulating layer, and the temperature of the fixed mold is set to 107°C to 114°C;

[0048] The depth of the guide groove of the master disk is preferably 15 nm to 40 nm. In this embodiment, a master disk having a guide groove with a depth of 25 nm is used.

[0049] A polycarbonate molten resin is injected into a molding die of a molding substrate, and a movable side of the molding die of the molding substrate is compressed to form an L0 molding substrate having a guide groove with a pitch of 180 nm by a manufacturing method of transferring the guide groove to the injected polycarbonate molten resin;

[0050] Regarding the thickness of the L0 molded substrate, the maximum thickness of the archived optical disc signal area is specified to be 1.4mm (for example, the standard for a 500GB archived optical disc). In order to use multiple discs stacked directly in an overlapping (stacked) state, a circular rib (protrusion structure) is provided on the inner circumference of the disc, and a gap is provided between the upper and lower optical disc signal surfaces that are not in direct contact. This structure prevents damage to the optical disc surface, data loss, and reading errors. Considering the warping and bending of the optical disc, the thickness of the signal area is required to be less than 1.3mm. If the thickness of the resin layer (about 0.1mm, about 0.2mm on both sides) and the adhesive resin layer (about 0.04mm) stacked on one side are considered, the thickness of the L0 molded substrate needs to be less than 0.53mm. In this thickness region, the rigidity relative to the molding temperature is low, and the substrate molding method of the present invention highlights its advantages. In addition, in this embodiment, 0.48mm is used as the thickness of the L0 molded substrate.

[0051] The molded substrate with guide grooves passes through the original plate of the fixed mold and the insulation layer, and is cooled by heat exchange between the fixed mold and the movable side. When the temperature of the molded substrate drops to 109°C to 115°C, it is taken out of the mold.

[0052] Specifically, Figure 8 The manufacturing process of a double-sided multi-layer optical disc is shown (hereinafter, a double-sided 8-layer optical disc is used as an example for explanation), including the following steps:

[0053] Molding step 0: Injecting polycarbonate molten resin at an injection temperature of 370° C. inside a molding die of a molding substrate to form a guide groove (transferring to form a fine groove structure). In the present invention, the guide groove refers to a groove portion for recording a signal;

[0054] Film forming step 0: forming a recording layer on a molded substrate having guide grooves by sputtering for recording and playing information. The molding step 0 and the film forming step 0 constitute the first layer of the optical disc;

[0055] Intermediate layer process 1: On the recording layer formed in film forming process 0, a liquid UV curable resin is applied by spin curing, and the transfer substrate supplied in molding process 1 is transferred by printing to form intermediate layer 1;

[0056] Forming process 1: forming a substrate for printing 180nm pitch guide grooves on the intermediate layer 1;

[0057] Film forming step 1: forming a recording layer with a thickness of tens of nanometers on the intermediate layer 1 by sputtering. The intermediate layer step 1, the molding step 1, and the film forming step 1 constitute the second layer of the optical disc;

[0058] Repeat the above process of forming the second layer of the optical disc to sequentially form the third layer and the fourth layer of the optical disc;

[0059] Protective layer engineering: In the fourth layer, liquid UV curing resin is applied by spin curing to form a protective layer for protecting the signal surface, thus completing the manufacturing of the half-side disc;

[0060] Bonding process: The opposite sides (back sides) of the two half-side discs to the sides where the guide grooves of the molded substrate are formed are bonded to each other to complete the manufacture of a double-sided eight-layer disc.

[0061] Although the AC tilt is affected by the heat load and stress in the manufacturing process of the double-sided eight-layer optical disc, the molding process 0 is the most important influencing factor.

[0062] Figure 6 The figure shows the relationship between the fixed mold temperature and the groove transfer rate. In the molding process, when the conventional injection molding method is used to mold 1TB with a narrow track pitch, in order to ensure the required transfer rate, the conventional molding technology needs to increase the mold temperature by 4°C for molding. However, due to the increase in mold temperature, the residual stress during molding becomes larger, and when the substrate is removed from the mold, the substrate temperature rises and the cooling proceeds rapidly, so Figure 7 As shown, the AC slope becomes larger.

[0063] In this application, the improvement is mainly aimed at the forming process 0 in the manufacturing process of 1TB optical discs, that is, the forming substrate of the single-sided optical disc is made using a forming substrate forming mold with an insulating layer, and the temperature of the fixed mold of the forming substrate forming mold is maintained at 107℃~114℃ during the manufacturing process. When the temperature of the forming substrate with the transfer guide groove is removed from the mold and reduced to 109℃~115℃, the residual stress in the forming process of the forming substrate can be effectively reduced, and the AC tilt problem of the forming substrate can be reduced, thereby improving the read and write performance of the optical disc.

[0064] In addition, the optical disc substrate molding mold of the present invention has a heat insulating layer and is suitable for molding optical disc substrates with 1 to 3 layers. By lowering the mold temperature during substrate molding, in the process of molding a guide groove substrate with a small pitch, it can be expected that the effect is to suppress the uniformity problem when the substrate is peeled off from the original disc due to insufficient cooling, thereby preventing transfer defects such as uneven deformation of the guide groove.

[0065] Specifically, Fig.13 and Fig.14 As shown, the fixed mold temperature of the molding substrate molding mold is compared with the temperature of the molding substrate with the transfer guide groove of the 1TB optical disc manufactured by the 1TB optical disc manufacturing method disclosed in the present invention and the 1TB optical disc manufactured by the existing optical disc manufacturing method when taken out from the molding substrate molding mold, and the AC tilt comparison analysis diagram.

[0066] from Fig.13It can be seen that in the existing optical disc manufacturing method, the temperature of the molded substrate with guide grooves when it is taken out from the molded substrate molding mold is about 125°C, and in the optical disc manufacturing method disclosed in the present application, the temperature of the molded substrate with guide grooves when it is taken out from the molded substrate molding mold is about 112°C. In order to ensure the read and write performance of a 1TB optical disc, the AC tilt of the double-sided optical disc must be controlled below 0.85°. In addition, the AC tilt of the single-sided optical disc molding substrate aims to be controlled below 0.40°. Fig.14 It can be seen that the AC tilt of the 1TB single-sided molded substrate manufactured by the optical disc manufacturing method disclosed in the present application is about 0.29°, while the AC tilt of the 1TB single-sided molded substrate manufactured by the existing method is about 0.53°. In order to ensure the read and write performance of the 1T optical disc, the AC tilt of the double-sided optical disc needs to be controlled below 0.85. The present invention reduces the fixed mold temperature of the molding substrate molding mold to 107°C to 114°C, and controls the temperature of the substrate removal to a temperature range of 109°C to 115°C, which is lower than the previous temperature. The rapid cooling deformation caused by the temperature difference between the temperature after removal and the air temperature is suppressed, and the AC tilt of the molded substrate and the double-sided optical disc can be controlled.

[0067] At the same time, if Fig.12 The figure shows a comparative analysis of the transfer rate and the fixed mold temperature of the molding substrate molding mold of the optical disc manufactured by the 1TB optical disc manufacturing method disclosed in the present invention and the optical disc manufactured by the existing optical disc manufacturing method. It can be seen from the figure that in the original disc of the present invention (track pitch 180nm), in order to ensure the necessary transfer rate of the guide groove, the fixed mold temperature of the molding substrate molding mold is reduced from 121°C in the original process to 111°C in the molding process of the present invention, and the mold temperature of the fixed mold (original disc side) of the molding substrate molding mold can be reduced by about 10°C.

[0068] Furthermore, the heat insulating layer can temporarily delay the heat exchange from the original plate to the fixed mold of the molding substrate molding mold.

[0069] Specifically, Figure 6 As shown, in order to ensure the uniformity of the transfer performance of the guide groove from the original disc to the polycarbonate, the temperature of the mold fixed side is as high as 121°C. Fig. 9 and Fig.10As shown in the figure, an insulating layer with low thermal conductivity is set between the mold fixed surface and the cooling water channel. During the time of filling the resin and completing the transfer, the heat exchange from the original disc to the molding substrate molding mold is temporarily delayed, so that the transfer performance of the original disc can be improved by maintaining the high temperature of the original disc surface before the transfer compression process is completed. Therefore, the temperature of the mold can be set to a lower temperature than before, and the molding substrate can be cooled more effectively during the cooling time after the transfer is completed, suppressing the deformation caused by sudden cooling due to the temperature difference with the air after removal, and achieving the effect of controlling the AC inclination.

[0070] Furthermore, the molding method of the molding substrate having the transfer guide groove is controlled as follows:

[0071] The time for injecting molten polycarbonate resin into the optical disc substrate molding mold ranges from 0.07 seconds at which no leakage of molten polycarbonate resin to the outside of the mold and burrs will occur, to 0.17 seconds at which the molten polycarbonate resin continues to solidify during the injection process but no underfilling of the original disc guide groove occurs.

[0072] The time from the start of the forming cycle to the removal of the formed substrate with guide grooves from the optical disk substrate forming mold is preferably from 3 seconds to 5 seconds to further obtain the effect of the present invention without causing significant warping (deformation) due to insufficient cooling, and is preferably 4 seconds in this embodiment.

[0073] Specifically, in some embodiments, the process is controlled by time, such as Fig.11 As shown, in this embodiment, the time for injecting the polycarbonate molten resin between the molding substrate and the original disc is 0.12s, and the time from the start of injecting the polycarbonate molten resin to taking the molding substrate with the transfer guide groove out of the molding substrate molding mold is 3.4s; compared with the optical disc substrate molding mold without an insulating layer, the optical disc substrate molding mold with an insulating layer temporarily delays the heat exchange from the original disc to the fixed side of the optical disc substrate molding mold during the process of filling the resin to obtain the transfer until the transfer compression is completed. By maintaining the high temperature of the original disc surface, the transfer performance of the guide groove can be improved. Therefore, the temperature of the mold can be set lower than before, and the mold can be cooled more effectively within the set time, so that the temperature of the molding substrate with the guide groove when it is taken out of the mold can be controlled between 109℃ and 115℃.

[0074] Furthermore, the heat insulating layer in the molding die of the molding substrate is made of ceramics having a lower thermal conductivity than traditional metal materials.

[0075] Furthermore, the temperature of the polycarbonate molten resin during injection is 340° C. to 390° C. Preferably, the temperature of the polycarbonate molten resin during injection is 390° C., which can avoid deterioration of warpage and discoloration of the polycarbonate resin caused by insufficient cooling at 340° C. during printing guide groove transfer.

[0076] Furthermore, the thickness of the molding substrate is 0.53 mm or less, and the spacing of the guide grooves (the interval between adjacent concave parts and convex parts) is 200 nm or less.

[0077] Furthermore, the method further includes forming more than four recording layers for recording playback information and a resin layer for separating the recording layers on the molded substrate having the transfer guide groove to form a single-sided optical disc;

[0078] Then, the molded substrates of the two single-sided optical discs are bonded to each other with the surfaces opposite to the surfaces having the guide grooves (the back surfaces of the single-sided optical discs) to form a double-sided optical disc.

[0079] A disc is formed by bonding two single-sided discs together, with 4 or more recording layers and 3 or more resin layers for separating the recording layers arranged on a molded substrate and one side thereof; the molded substrate of the single-sided disc is manufactured according to the disc manufacturing method disclosed in the present invention.

[0080] The optical disc disclosed in the present application is formed by bonding two single-sided optical discs together, and each single-sided optical disc includes a molded substrate and four or more recording layers arranged on one side of the molded substrate; the molded substrate of each of the single-sided optical discs is manufactured using the optical disc manufacturing method described in the present application, which can effectively reduce the residual stress in the molding process of the molded substrate, thereby reducing or eliminating the AC tilt problem of the molded substrate, thereby improving the read and write performance of the optical disc.

[0081] Furthermore, the thickness of the molding substrate is 0.53 mm or less, and the spacing between the guide grooves is 200 nm or less.

[0082] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for manufacturing an optical disc, characterized in that: The manufacturing process of forming a molded substrate with a guide groove includes the following steps: An insulating layer is provided on the fixed mold side of the molding substrate molding mold, and a master plate for transferring the guide groove to the molding substrate is provided on the insulating layer. The fixed mold temperature of the molding substrate molding mold is set to 107° C. to 114° C., and the insulating layer is used to temporarily delay heat exchange between the master plate and the fixed mold of the molding substrate molding mold; A polycarbonate molten resin is injected into the molding substrate molding die, and a movable side of the molding substrate molding die is compressed to form a molding substrate by a manufacturing method in which the guide groove is transferred to the injected polycarbonate molten resin; The molded substrate with guide grooves is cooled by heat exchange between the fixed mold and the movable side through the original plate and the insulation layer of the fixed mold. When the temperature of the molded substrate drops to 109°C to 115°C, the molded substrate with guide grooves is taken out from the molding substrate molding mold.

2. The optical disc manufacturing method according to claim 1, characterized in that: The molding method of the molding substrate with transfer guide grooves is controlled as follows: the time for injecting the polycarbonate molten resin into the molding substrate molding mold is 0.07s to 0.17s; the time from the start of injecting the polycarbonate molten resin to taking the molding substrate with transfer guide grooves out of the molding substrate molding mold is 3 to 5s.

3. The optical disc manufacturing method according to claim 1, characterized in that: The heat insulating layer in the molding die of the molding substrate is made of ceramic.

4. The optical disc manufacturing method according to claim 1, characterized in that: The temperature of the polycarbonate molten resin during injection is 340° C. to 390° C.

5. The optical disc manufacturing method according to claim 1, characterized in that: The thickness of the molded substrate is 0.53 mm or less.

6. The optical disc manufacturing method according to claim 1, characterized in that: The pitch of the guide grooves is 200 nm or less.

7. The optical disc manufacturing method according to any one of claims 1 to 6, characterized in that: The method further includes forming four or more recording layers for recording and playing information on a molded substrate having a transfer guide groove, and forming a resin layer for separating the recording layers to form a single-sided optical disc; Then, the surfaces of the two single-sided optical discs opposite to the surfaces having the guide grooves are bonded to each other to form a double-sided optical disc.

8. An optical disc, characterized in that: It comprises two single-sided optical discs bonded together, with 4 or more recording layers and 3 or more resin layers for separating the recording layers arranged on a molded substrate and one side thereof; the molded substrate of the single-sided optical disc is manufactured according to any one of the optical disc manufacturing methods according to claims 1 to 7.

9. The optical disc according to claim 8, characterized in that: The thickness of the molded substrate is 0.53 mm or less.

10. The optical disc according to claim 8 or 9, characterized in that: The pitch of the guide grooves is 200 nm or less.

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