JP2009020966A - Optical disk substrate molding stamper and optical disk substrate molding stamper manufacturing method - Google Patents

Abstract

An optical disk substrate molding stamper that suppresses warping of a stamper while maintaining the adhesion between a substrate layer and a heat insulating layer, and a method for manufacturing the same.
The heat insulating layer 3 is a spin that applies a varnish material obtained by dissolving a polyamideimide resin in an N-methyl-2-pyrrolidone (NMP) solvent onto the back surface 2b of the substrate layer 2 while rotating the substrate layer 2. The steps of coating and heating / drying by a coating method are repeated three times to form resin layers 3a, 3b, and 3c made of three layers of polyamideimide resin having a substantially equal thickness of 35 μm. Thus, the heat insulating stamper having the three resin layers has good heat insulating properties by making the heat insulating layer 3 105 μm thicker than the conventional 35 μm thickness, and has good adhesion between the substrate layer and the heat insulating layer. It is possible to easily and reliably manufacture a stamper that is good and has reduced warpage.
[Selection] Figure 1

Description

  The present invention relates to an optical disk substrate molding stamper and a manufacturing method thereof, and in particular, an optical disk substrate molding stamper in which a heat insulating layer made of a heat-resistant synthetic resin is formed on a substrate layer made of a metal having a fine concavo-convex pattern. It relates to a manufacturing method.

  2. Description of the Related Art Conventionally, an optical disk substrate molding stamper used in an optical disk substrate molding die for injection molding of an optical disk substrate has an optical disk substrate on the surface in order to appropriately transfer a fine uneven pattern onto the surface of the optical disk substrate during injection molding. A heat insulating stamper is used in which a heat insulating layer made of a heat resistant resin is formed on a substrate layer made of a metal such as nickel (Ni) having a fine concavo-convex pattern in which the concavo-convex pattern on the surface is reversed. However, the formation of the heat insulating layer has a problem in that the stamper is warped during manufacturing.

  A method for manufacturing a stamper for forming an optical disk substrate will be described with reference to FIG. FIG. 4 is a schematic diagram simply showing the manufacturing steps (A) to (H) of a stamper for forming an optical disk substrate. The heat insulation stamper 10 first electroformed Ni on a master die 1 (see FIG. 4A) on which a fine uneven pattern identical to the fine uneven pattern formed on the optical disk substrate surface (not shown) is formed, The Ni substrate layer 2 having a fine uneven pattern is formed on the surface corresponding to the transfer surface of the stamper (see FIG. 4B). Next, a varnish material in which a heat-resistant synthetic resin such as polyamideimide is dissolved in a solvent is applied onto the Ni substrate layer 2 by spin coating (see FIG. 4C), and the solvent is evaporated by heating and drying. Then, the heat insulating layer 3 made of a heat resistant synthetic resin is formed (see FIG. 4D). Then, a convex warp occurs on the matrix 1 side due to the volume shrinkage of the heat insulating layer 3, and tensile stress is generated because the vicinity of the interface with the Ni substrate layer 2 in the heat insulating layer 3 is constrained.

  Next, the conductive film 6 is formed on the heat insulating layer 3, and the electroformed jig 4 is provided on the laminate including the mother die, the Ni substrate layer 22, and the heat insulating layer 3 (see FIG. 4E). Then, the warp described above is corrected horizontally by the structure of the jig 4, and more tensile stress is generated in the heat insulating layer 3. Therefore, when the Ni support layer 5 is formed on the conductive film 6 by performing nickel electroforming using the conductive film 6 as a cathode (see FIG. 4F), the Ni support layer 5 has a tensile electroforming stress. Will occur. This electroforming stress is an internal stress generated with electroforming conditions for obtaining characteristics (for example, hardness) necessary for the Ni support layer 5 of the heat insulating stamper 10 for optical disk molded substrates. Next, when the laminate composed of the matrix 1, the Ni substrate layer 2, the heat insulating layer 3, the conductive film 6, and the Ni support layer 5 is removed from the electroforming jig 4, the tensile stress in the Ni support layer 5 and the heat insulating layer 3 is removed. Is released, and the matrix 1 side warps convexly as a whole of the laminate (see FIG. 4G). At this time, tensile stress remains in the vicinity of the interface between the Ni support layer 5 and the heat insulating layer 3 and in the vicinity of the interface of the heat insulating layer 3 with the Ni substrate layer 2. Therefore, when the laminated body composed of four layers of the Ni substrate layer 2, the heat insulating layer 3, the conductive film 6, and the Ni support layer 5, that is, the heat insulating stamper 10, is peeled off from the mother die 1, the above warpage is caused by the above residual stress. Is reduced (see FIG. 4H).

  By using the stamper 10 manufactured as described above for injection molding of an optical disk substrate, high transferability can be obtained by a high transfer temperature, and at the same time, a molding cycle can be shortened by setting a low mold temperature. . Therefore, in order to further increase the productivity, that is, to shorten the molding cycle in a higher dimension, a means of increasing the thickness of the heat insulating layer 3 in the heat insulating stamper 10 can be considered.

  However, during the injection molding, the warp is reduced as described above until the heat insulating stamper 10 can be vacuum-adsorbed and fixed in the optical disk substrate molding die (the flatness is 1 μm or less). Is about 300 μm while the thickness of the heat insulating layer 3 is 35 μm or less. When the heat insulating layer is formed as a single layer from the conventional heat insulating stamper in the same manner as in the above manufacturing process, for example, thicker than 100 μm and 35 μm, the residual stress in the heat insulating layer 3 becomes too large. When 10 was peeled off, as shown in FIG. 5, it was confirmed by experiments that the Ni support layer 5 side warped convexly. This warpage cannot be ignored when the optical disk substrate is injection-molded (the flatness is greater than 1 μm).

As a method for correcting the warping of the stamper, for example, as described in Patent Document 1, a heat insulating stamper is manufactured using an electroformed jig having a convex surface, and the stamper is peeled off from the mother mold. A method of post-curing at a temperature of 230 ° C. is known.
JP 2001-236697 A

  However, when a heat insulating stamper is manufactured using the method described in Patent Document 1, there is a problem that a problem arises in the adhesion between the Ni substrate layer and the heat insulating layer.

  The present invention has been made in view of the above circumstances, and provides an optical disk substrate molding stamper that suppresses the warping of the stamper while maintaining the adhesion between the substrate layer and the heat insulating layer, and a method for manufacturing the same. With the goal.

In order to solve the above-mentioned problem, the invention described in claim 1 includes a substrate layer made of a metal having a concavo-convex pattern on the surface, a heat insulating layer made of a synthetic resin formed on the back surface of the substrate layer, and the heat insulation. In a stamper for forming an optical disk substrate provided with a support layer made of metal on the layer,
The heat insulating layer is formed of a plurality of layers.

In the invention of claim 2, a metal substrate layer is formed by electroforming on the surface having the concave-convex pattern of the matrix, and a varnish material in which a synthetic resin is dissolved in a solvent is applied on the substrate layer, followed by drying by heating. Then, a heat insulating layer of the synthetic resin is formed, and a metal support layer is formed on the heat insulating layer by electroforming, and then the optical disk substrate having a concavo-convex pattern on the surface by peeling the matrix from the substrate layer In a manufacturing method of an optical disk substrate molding stamper for manufacturing a molding stamper,
The heat insulation layer is formed in a plurality of layers by repeating the steps of applying and heating and drying the varnish-like material a plurality of times.

Further, the invention of claim 3 is a method of manufacturing a stamper for molding an optical disk substrate according to claim 2,
The plurality of layers of the heat insulating layer are formed so as to be thinner from the substrate layer toward the support layer.

The invention of claim 4 is the method of manufacturing a stamper for forming an optical disk substrate according to claim 2 or 3,
The heat insulating layer is formed by spin coating a varnish material in which polyamideimide is dissolved in an N-methyl-2-pyrrolidone solvent.

  ADVANTAGE OF THE INVENTION According to this invention, the stamper for optical disk board | substrate shaping | molding which suppressed the curvature of a stamper can be provided in the state which maintained the adhesive force of a board | substrate layer and a heat insulation layer by forming a heat insulation layer by several layers. .

  In addition, according to the present invention, the step of applying the varnish-like material to the heat insulating layer and heating and drying it is repeated a plurality of times to form a plurality of layers, thereby maintaining the adhesion between the substrate layer and the heat insulating layer. Thus, it is possible to provide a manufacturing method of a stamper for forming an optical disk substrate in which the warpage of the stamper is suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a schematic configuration of an optical disk substrate molding stamper according to an embodiment of the present invention. The stamper for forming an optical disk substrate according to the present embodiment has a spiral microscopic unevenness having a depth d of 10 μm or less and a width w of 100 μm or less, where the unevenness is reversed from the uneven pattern on the surface of the optical disk substrate (not shown). A Ni support made of Ni metal formed on the heat insulating layer 3 via a conductive film 6 on the back surface 2b of the substrate layer 2 made of Ni metal having the pattern 2a and having a heat insulating layer 3 made of polyamideimide resin. Layer 5 is provided. The substrate layer 2 and the Ni support layer 5 may be made of a metal other than Ni metal. However, when Ni metal is used, it is preferable because it has appropriate hardness and good durability.

  The heat insulating layer 3 is formed on the back surface 2b of the substrate layer 2 while rotating the substrate layer 2 with a varnish material obtained by dissolving a polyamideimide resin in an N-methyl-2-pyrrolidone (NMP) solvent, as will be described later. The steps of coating and heating and drying are repeated three times by a spin coating method, and the resin layers 3a, 3b, and 3c are formed of three layers of polyamideimide resin each having a thickness of about 35 μm. Thus, the heat insulating stamper having the heat insulating layer 3 composed of the three resin layers 3a, 3b, and 3c suppresses the warp of the stamper, and further increases the heat insulating layer 3 to 105 μm thicker than the conventional thickness of 35 μm. As a result, the heat insulation effect is increased and the production efficiency can be increased. The heat insulating layer 3 is not limited to the polyamide-imide resin, but may be any synthetic resin having heat resistance that does not soften at 100 ° C. However, the polyamide-imide resin has high heat resistance, and injection molding of the optical disk substrate. It is suitable because it can withstand deformations of time.

  When the heat insulating layer 3 of 100 μm or more is formed as a single layer using a varnish material in which a synthetic resin is dissolved in a solvent, as described above, the stress remaining in the heat insulating layer 3 becomes too large, and the Ni support layer 5 Due to the relationship between the force and the stress remaining inside, as shown in FIG. 5, warping occurs such that the Ni support layer 5 side becomes convex. As a result, the flatness of the Ni support layer 5 becomes larger than 1 μm, and it becomes difficult to appropriately fix the stamper in the optical disk substrate molding die by vacuum suction.

  However, as shown in FIG. 1 of the present embodiment, when the 105 μm heat insulating layer 3 is divided into three resin layers 3a, 3b and 3c in the thickness direction, the resin layers 3a, 3b and 3c are divided. Since the shrinkage energy accompanying the volume shrinkage due to the evaporation of the solvent in the varnish-like material is released each time the varnish-like material is formed, the stress finally remaining in the heat insulating layer 3 is larger than that in the case where it is formed as a single layer. It gets smaller. By doing so, even if the heat insulation layer 3 becomes thick, warping of the stamper is suppressed from the relationship of the force in the stamper as in the case of FIG.

  Furthermore, the resin layer 3a formed on the Ni substrate layer 2 has substantially the same thickness as the heat insulating layer in the conventional stamper, has good adhesion to the substrate layer 2, and can be peeled off from the substrate layer 2. Suppress. Furthermore, since the resin layers 3b and 3c formed on the resin layer 3a are also made of the same resin and have a thin layer thickness, the adhesiveness between these resin layers is good, and the substrate layer 2 of the heat insulating layer 3 is good. Can be prevented.

  FIG. 2 shows the relationship between the number of divided layers of the heat insulating layer 3 and the flatness of the stamper to be manufactured. FIG. 2 shows the stamper flatness measured when the heat insulating layer having a total thickness (A) of 100 μm is changed from a single layer to a plurality of layers in the stamper manufacturing method based on FIG. In this case, the number of divided layers “1” of the heat insulating layer is one heat insulating layer and the thickness thereof is A, and the number of divided layers “2” of the heat insulating layer is composed of two heat insulating layers. The thickness of A is A / 2. The number of divided layers of the heat insulating layer “3” is that the heat insulating layer is composed of three layers, and the individual thicknesses of the heat insulating layers are A / 3. Hereinafter, the same applies to the number of divided layers 4, 6, and 8 of the heat insulating layer.

  In order to obtain a heat insulating layer in a warped state (flatness of 1 μm or less) of the stamper that can be vacuum-adsorbed into the mold during injection molding, from the relationship between the heat insulating layer having a plurality of layers and the flatness of the stamper. Obviously, it may be divided into three or more layers. In the present invention, the total thickness of the heat insulating layer is 35 to 300 μm, preferably 50 to 200 μm. The thickness of the individual resin layers constituting the heat insulating layer varies depending on the number of the heat insulating layers. However, the maximum thickness of the resin layer is about 50 μm, and preferably 40 μm or less.

  When such a stamper is vacuum-adsorbed and fixed in a mold for producing an optical disk substrate, and a resin is injection-molded in the mold, an optical disk substrate on which the uneven surface 2a of the substrate layer 2 of the stamper 10 is well transferred is obtained. Manufactured.

  Next, an optical disk substrate molding stamper manufacturing method including the heat insulating layer 3 having a plurality of divided resin layers will be described based on examples.

[Example 1]
FIG. 3 is a schematic diagram simply showing the manufacturing steps (A) to (I) of the stamper for forming an optical disk substrate according to the first embodiment of the present invention. First, before the manufacturing process shown in FIG. 3, a conductive film is formed on a fine uneven pattern formed on a glass master (not shown), and Ni electroforming is performed on the conductive film, and then peeled off from the glass master. By doing so, a master stamper not shown in the figure is obtained. Further, the master stamper is subjected to a release film treatment, Ni electroforming is performed, and the master stamper is peeled from the master stamper to obtain a mother stamper 1 as a mother die. Then, the mother die 1 is subjected to a release film treatment similarly to the master stamper (see FIG. 3A). Then, as shown in FIG. 3B, Ni metal is electroformed on the mother die 1, and a spiral microscopic surface having a depth d of 10 μm or less and a width w of 100 μm or less is formed on the stamper transfer surface. An Ni substrate layer 2 having a pattern is formed.

  Next, a varnish-like material obtained by dissolving polyamideimide (for example, Viromax HR16NN; manufactured by Toyobo Co., Ltd.), which is a heat insulating material, with an N-methyl-2-pyrrolidone (NMP) solvent is applied onto the Ni substrate layer 2 by the spin coating method described above. (See FIG. 3C), the solvent is evaporated at a temperature of 100 ° C. and heat-cured to form a resin layer 3a having a thickness of 25 μm (see FIG. 3D). The process of heating and curing such a varnish-like material is repeated four times until the heat insulation layer has a desired thickness (100 μm in this case), and the heat insulation layer composed of the resin layers 3a, 3b, 3c, and 3d. 3 is formed (see FIG. 3E). Then, the 100 μm heat insulating layer 3 having the four-layer structure reduces the warpage of the entire laminate including the matrix 1, the Ni substrate layer 2, and the heat insulating layer 3 as compared with the case where a single layer 100 μm heat insulating layer is formed. It will be formed in the state.

  Next, after forming the conductive film 6 on the heat insulating layer 3, an electroforming jig 4 for forming the Ni support layer 5 on the laminate composed of the matrix 1, the Ni substrate layer 2, the heat insulating layer 3, and the conductive film 6. Equipped. At this time, due to the structure of the electroforming jig 4, the warp of the laminate shown in FIG. 3E is corrected horizontally (see FIG. 3F). Then, a tensile stress that tends to shrink is generated in the heat insulating layer 3. In this state, Ni metal is electroformed on the conductive film 6 to form the Ni support layer 5 (see FIG. 3G), and when the electroforming jig 4 is removed, as shown in FIG. A convex warp occurs on the side of the matrix 1. This warpage is caused by the tensile internal stress in the Ni support layer 5 and the tensile stress in the heat insulating layer. Here, as the electroforming conditions, electroforming conditions suitable for obtaining characteristics (for example, hardness) required for the stamper are used.

  In this case, in the state before the stamper 10 composed of the Ni substrate layer 2, the heat insulating layer 3, the conductive film 6, and the Ni support layer 5 is peeled off from the mother die 1, the heat insulating layer 3 in the Ni support layer 5 still remains. The stress that tends to shrink remains in the vicinity of the interface and in the heat insulating layer 3. Next, when the stamper 10 is peeled off from the mother die 1, the residual stress brings the stamper 10 into a state where the stamper 10 can be vacuum-adsorbed to the die (flatness is 1 μm or less) as shown in FIG.

  As described above, the process of heat-curing the heat insulating layer 3 after applying the varnish-like material was repeated a plurality of times without essentially changing the stamper manufacturing method. Although it is a thick heat insulating layer, it is possible to easily and reliably manufacture a stamper in which the adhesion between the substrate layer and the heat insulating layer is good and the warpage is suppressed.

[Example 2]
The optical disk substrate molding stamper 10 is manufactured in the same manner as in the first embodiment. However, when the heat insulating layer 3 of 100 μm is formed, the first layer from the Ni substrate layer 2 side is 40 μm, the second layer is 30 μm, the third layer is 20 μm, and the fourth layer is 10 μm. As a result, like the first embodiment, the stamper 10 can be vacuum-sucked to the optical disk substrate molding die (the flatness is 1 μm or less). Here, the curvature due to the warp of each of the layers 3a, 3b, 3c, and 3d of the heat insulating layer 3 divided and formed in the state of FIG. 3 (E) described above is larger as the layer is closer to the Ni substrate layer 2, and as a result, the stamper warps. It is also effective to incline the residual shrinkage stress of each layer in order to reduce the stress, and the stress that tends to shrink as the resin layer has a larger thickness and a larger volume. The thickness was inclined.

[Comparative Example 1]
An optical disc substrate molding stamper is manufactured in the same manner as in the first embodiment. However, when forming a heat-insulating layer of 100 μm, it is formed as a single layer rather than a multilayer. As a result, the shrinkage residual stress of the heat insulation layer was too large, the stamper was warped and deformed, and the flatness became larger than 1 μm, and it was not possible to vacuum-adsorb to the mold.

  As described above, since the stampers obtained in Examples 1 and 2 according to the present invention have a multilayered heat insulating layer, as shown in Comparative Example 1, a stamper having a single heat insulating layer having the same thickness is While the warp deformation occurred and the vacuum could not be properly sucked into the mold, the warp deformation of the stamper was suppressed, and the vacuum was able to be properly sucked into the mold.

  In addition, since the varnish-like material for forming the heat insulating layer 3 has a high viscosity, when the heat insulating layer is formed as a single layer using the spin coat method, the in-plane variation in thickness increases. . However, as described above, as shown in the embodiment according to the present invention, when the heat insulating layer 3 is made multilayer, in-plane variation in thickness is reduced. Furthermore, when the heat insulating layer is divided into multiple layers using a varnish-like material, there is an advantage that the thickness of the heat insulating layer can be freely controlled as compared with the case where a film made of a heat insulating material is used.

It is sectional drawing which shows schematic structure of the optical disk substrate shaping stamper of one Embodiment by this invention. 4 is a table showing the relationship between the number of divided layers of a heat insulating layer and the flatness of a stamper in an optical disk substrate molding stamper according to the present invention. It is the schematic diagram which showed simply the manufacturing process (A) to (I) of the stamper for optical disk substrate shaping | molding shown in Example 1 by this invention. It is the schematic diagram which showed simply the manufacturing process (A) to (H) of the conventional stamper for optical disk substrate shaping | molding. It is sectional drawing which shows the curvature deformation | transformation state of the stamper for optical disk substrate shaping | molding which has the conventional thick heat insulation layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mother mold 2 Substrate layer 3 Heat insulation layer 3a, 3b, 3c, 3d Resin layer 4 Electroforming jig 5 Support layer 6 Conductive film 10 Stamper

Claims (4)

For forming an optical disk substrate comprising a substrate layer made of metal having a concavo-convex pattern on the surface, a heat insulating layer made of synthetic resin formed on the back surface of the substrate layer, and a support layer made of metal on the heat insulating layer In the stamper
The stamper for molding an optical disk substrate, wherein the heat insulating layer is formed of a plurality of layers. A metal substrate layer is formed by electroforming on the surface having the concave and convex pattern of the matrix, and a varnish material in which synthetic resin is dissolved in a solvent is applied on the substrate layer, followed by heating and drying to form a heat insulating layer of synthetic resin Then, a metal support layer is formed on the heat insulating layer by electroforming, and then the optical disk substrate molding for producing an optical disk substrate molding stamper having a concavo-convex pattern on the surface by peeling the matrix from the substrate layer. In the manufacturing method of the stamper for
The method for manufacturing a stamper for forming an optical disk substrate, wherein the heat insulating layer is formed into a plurality of layers by repeating the steps of applying the varnish-like material and heating and drying the plurality of times. In the manufacturing method of the optical disk substrate forming stamper according to claim 2,
The method for manufacturing a stamper for forming an optical disk substrate, wherein the plurality of layers of the heat insulating layer are formed thinner from the substrate layer toward the support layer. In the manufacturing method of the optical disk substrate forming stamper according to claim 2 or 3,
A method for producing a stamper for molding an optical disk substrate, wherein the heat insulating layer is formed by spin coating a varnish material in which polyamideimide is dissolved in an N-methyl-2-pyrrolidone solvent.

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