JPS624893A - Electrocasting device - Google Patents

Abstract

PURPOSE:To make the thickness of an electrocast film and the thickness of a stamper uniform by providing a discoid anode wherein an electrode is not present at a part of the site corresponding to the peripheral edge part of a master disk to the titled electrocasting device. CONSTITUTION:An electrocasting device is furnished with a cathode 2 for holding a master disk 5 and an anode 3 which is set opposite to the master disk 5 held by the cathode 2 at a prescribed distance from the disk 5. The cathode 2 holding the master disk 5 is rotated by a motor 1 and relatively rotated at a prescribed distance from the anode 3 and electrocasting is carried out. The anode 3 is formed so that a part of the outer periphery of the anode 3 is positioned on the inside of the outer periphery of the master disk 5 in the direction of the rotation axis of the rotational motion and other parts of the anode 3 are placed at the same position as the outer periphery of the master disk 5 or on the outside of the disk 5.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an electroforming device, and more specifically, it is possible to obtain a stamper with good transferability of a fine pattern from a master and a uniform film thickness. The present invention relates to an electroforming device having an anode having a novel structure.

[Technical background of the invention and its problems]

When manufacturing records, a thin disc-shaped metal plate called a stamper is usually used.

This stamper is usually manufactured by the following process. That is, first, a master disc is created by carving a recording pattern in the form of grooves on a lacquer plate using a needle.

Next, a conductive layer is formed on this master by silver mirror reaction or the like, and then a nickel plating film with a thickness of 200 to 300 μm is formed thereon, and this nickel plating film is peeled off from the master to form a mask.

Next, after performing a peeling treatment on the mask surface, a nickel plating film is further formed, and this is peeled off from the mask to serve as a mother. Furthermore, after performing a peeling treatment on the mother surface, a nickel plating film is formed on the mother, and this is peeled off from the mother to serve as a mask.

The above process is a process applied during normal record manufacturing, but in the case of a high-density recorded disc, it is usually performed as follows. The production of disc master discs is
For example, this is carried out by applying a photosensitive resin onto a glass substrate and optically etching the resulting resin film, resulting in a master disk on which a fine pattern is engraved.

Even in the case of the above-mentioned high-density recording disk, the process of obtaining a stamper from the master disc is the same as in the case of the above-mentioned record.

However, since the master disc in this case is a master disc on which a fine pattern is formed, the following problems occur in the process of Sokel plating on nickel electroforming.

When an anode made of soluble nickel is used as an anode in the electroforming process, the melted metal (sokel) may oxidize near the anode, forming a slime of insoluble precipitates, or oxidize on the anode surface. The problem is that the slime and smut are incorporated into the nickel film and damage the fine pattern. Furthermore, as the nickel anode melts, the distance between the anode and the cathode changes, resulting in uneven nickel film thickness.

These problems can be solved by using an unmeltable anode as the anode, as disclosed in Japanese Patent Application Laid-Open No. 58-157984.

However, even if the above-mentioned insoluble anode is used,
Furthermore, there were the following problems. Usually, electroforming equipment is
As shown in the figure, a rotatable cathode 2 connected to a motor 1 and an insoluble anode 3 facing the cathode 2 are provided in an electrodeposition tank 4. A disc-shaped master 5 is attached to the cathode 2 . The anode 3 is usually formed into a disk shape corresponding to the disk-shaped master 5.

When performing nickel electroforming with an electroforming apparatus having such an electrode configuration, electroforming is performed without rotating the master plate attached to the cathode. As a result, although a nickel film is formed on the surface of the master, the thickness of the film differs between the center and the periphery of the master, being thicker at the periphery. Therefore, a problem has arisen in that the thickness of the obtained stamper, and furthermore the thickness of the disk obtained using this stamper, becomes non-uniform.

[Object of the Invention] An object of the present invention is to solve the above problems and provide an electroforming apparatus that has good transferability of a fine pattern from a master and is capable of obtaining a stamper with a uniform film thickness. With the goal.

[Summary of the invention]

As a result of extensive research to achieve the above-mentioned object, the present inventors have found that the unevenness of the thickness of the nickel film as described above,
In particular, we investigated the cause of the phenomenon in which the film thickness is larger at the periphery than at the center, and found that this phenomenon is due to the so-called edge effect, in which an excessive amount of current flows from the anode side to the periphery of the master (cathode side). We obtained the knowledge that

Therefore, if the disk-shaped anode of the electroforming device is constructed so that no electrode is present in a part of the area corresponding to the peripheral edge of the master, when the master rotates, the peripheral edge of the master will be removed from the area where the electrode is present (the anode )
As a result, the concentration of current on the peripheral edge of the master is alleviated, and the thickness of the electroformed film and the thickness of the stamper can therefore be made uniform. The idea was obtained and the present invention was completed.

That is, the electroforming apparatus of the present invention includes a cathode that holds a master disc, an anode that is provided facing the master disc held by the cathode at a predetermined distance, and a cathode and an anode that hold the master disc. In the electroforming apparatus, the shape of the anode viewed from the direction of the axis of rotation of the rotary motion is such that a part of the outer periphery of the anode is The anode is characterized in that it is located inside the outer periphery of the master disc, and another part of the outer periphery of the anode is located at the same position as the outer periphery of the master disc or outside of it.

As shown in FIG. 1, such an anode includes an anode 6 having a structure in which a notch is provided in a disk whose diameter is, for example, the same size as the original disk, and an anode 6 whose diagonal length is, for example, the same size as the original disk, as shown in FIG. Examples include a square anode 23 having the same size as the diameter of the master disc, and an elliptical anode 24 having a long axis having the same length as the diameter of the original disc, as shown in FIG. Among these anodes, an anode having a structure in which a notch is provided in a disk is preferred.

Hereinafter, an anode having a notch will be explained.

The anode has a structure in which a disc-shaped anode has a notch.
As shown in the figure, the anode 6 has a structure in which a notch 7 with a predetermined expansion and softness is provided from the outer edge of the disk-shaped anode 6 toward the center.

In the present invention, the size and shape of the notch.

The number etc. are not particularly limited. For example, the example shown in FIG. 1 is a fan-shaped notch 7, and the cut line 6a of the anode 6 extends to the center of the disk. On the other hand, the example shown in FIG. 2 has a fan-shaped cutout 9, but the cut line 8a of the anode 8 does not reach the center O of the disk, and the angle of the fan shape is also smaller than that shown in FIG. It has a wide angle. Further, the example shown in FIG. 3 is not a fan-shaped cutout but a semicircular cutout 11. The example shown in FIG. 4 is an example in which a plurality of fan-shaped notches 13 are provided.

The example described above is an example in which the notch in the anode is fixed, but in practice there are cases where it is desired to change the film thickness at the peripheral edge of the electroformed film depending on the situation. In order to cope with this problem, it is preferable to use an anode structure in which the shape and area of the notch can be changed.

For example, as shown in FIGS. 5 and 6, a fan-shaped second anode 15 is brought into close contact with the back side of the first anode 14 in which a predetermined notch is provided, and the second anode 15 is rotated about the center 0. It is better to have a structure where it can be attached. By making the second anode 15 movable with respect to the first anode 14 in this way, it is possible to change the shape and area of the notch 16 formed by the first anode 14 and the second anode 15. It is useful. For example, when reducing current concentration in a wide area from the periphery to the center of the electroformed film, the second anode 15
The position of the second anode 15 may be set so that the notch 16 has a large shape.If the current concentrated relaxation is to be applied only to the vicinity of the periphery of the master, the position of the second anode 15 may be set as shown in FIG. The notch 17 may be formed only on the peripheral edge.

Further, regarding the score line, it is preferable to make it not a straight line like the score line 6a in FIG. 1, but a curve like the line 15a corresponding to the score line of the second diagonal 15 in FIG. 5.

This is because when the score line is straight, the thickness of the electroformed film in the area sandwiched between the center and the periphery tends to be smaller than that at the center and the periphery; This is because, in such a case, such non-uniformity in film thickness will not occur.

Regarding the material of the insoluble anode used in the present invention, it is preferable to use a nickel plate coated with gold or platinum, or a titanium plate coated with gold or platinum.

An electroforming device incorporating the above-mentioned anode is usually configured as follows. As shown in FIG. 9, the electrodeposition tank 4
A plating solution 18 is filled within the plating solution, and a cathode 2 that is rotatable by being connected to the motor 1 and an anode 3 that is connected to a power source 19 are disposed within the plating solution. And plating solution 18
is configured to be circulated between the electrodeposition tank 4 and the dissolution tank 20 by a circulation pump 21, and a clean plating solution is supplied into the electrodeposition tank 4 through a filtration filter 22. There is. It should be noted that the present invention is also applicable to an apparatus in which the master is fixed and the anode is rotated. Furthermore, if the master rotates relative to the anode,
It is also applicable to an apparatus configured to rotate both the master disk and the anode.

In such an electroforming apparatus, when performing electroforming, a master disk 5 on which a fine pattern is formed is attached to the cathode 2, and the master disk 5 is rotated by the motor 1 before electroforming is performed. At this time, if the anode of the present invention as described above is used as the anode 3, as the master 5 rotates, the peripheral edge of the master 5 will alternately face the part where the anode is present and the part where the anode is not present. As a result, the concentration of current on the peripheral edge of the master is alleviated.

[Embodiments of the invention]

EXAMPLE Nickel plating was carried out under the following conditions using an electroforming apparatus having the configuration shown in FIG.

First, a photosensitive resin is coated on a glass plate as a master, and the resulting resin film is optically etched to form a fine pattern, and then a film with a thickness of 300 mm is applied on top of this to impart conductivity.
~1000 master discs on which gold evaporated films were formed were prepared.

The master disc was attached to the cathode with the surface of the master disc on which the fine pattern was formed facing the anode side.

As the anode, an insoluble anode made of a titanium plate coated with platinum was used, and its structure consisted of a first anode 14 and a second anode 15 as shown in FIG.

That is, the first anode 14 has a diameter of 360 mm, and the notch portion (the notch portion formed only by the first anode) is centered at 0.
It was made into a fan shape having an angle of 90 degrees.

The second anode 15 had a fan shape with an angle of 120°. and,
A portion 15b of the second anode 15 overlapping with the first anode 14 was set at an angle of 60°. Note that the line 15a corresponding to the incision line of the second anode 15 was a curved line with a radius of curvature of 180 mm.

The distance between the first anode and the cathode is 40 mm.
was set to face the master disc 5, and the master disc 5 was rotated at 1100 rpm by the motor 1 to perform nickel electroforming. The plating solution used at this time was 600 g of nickel sulfamate/β, 40 g of boric acid/C bit inhibitor (trade name Nystar 806, manufactured by Uezai Kogyo Co., Ltd.) 1
mj! /l was considered to be a bath.

In addition, plating bath temperature: 45°C2 current density: 12A/al
, under the condition of plating bath pH 4.2 ± 0.2, thickness 25
Electroforming was performed until a 0 μm nickel electroformed film was obtained.

In addition, in order to prevent a decrease in nickel concentration and pH in the plating bath, nickel carbonate (NiC
By adding O9・2Ni (OH)2・4H20),
The nickel concentration and pH of the plating bath were maintained at the initial values.

After the electroforming was completed, the electroformed film was peeled off from the master, and a nickel electroformed film with gold attached to the surface was obtained.

The obtained nickel electroformed film was used as a stamper for forming an optical disc.

The film thickness of this nickel electroformed film stamper was measured from the center of the stamper toward the peripheral edge, and the results are shown as curve a in FIG. 10.

As a comparative example, the structure of the anode was a simple disk (diameter 3
Nickel electroforming was performed in the same manner as in the example except that a material having a diameter of 60 mm) was used. The film thickness was measured in the same manner as in the example, and the results are shown as a curve in FIG.

From the above results, when the anode of the present invention is used, the thickness of the stamper does not change significantly even near the peripheral edge of the stamper, and the thickness of the stamper as a whole becomes uniform. On the other hand, in a comparative example, that is, when an anode having a conventional structure was used, the film thickness of the stamper differed widely between the peripheral portion and the rest, for example, by a maximum of 70 μm, and non-uniformity in film thickness was observed.

〔Effect of the invention〕

As described in detail above, by using the electroforming apparatus of the present invention having an anode with a novel structure, a stamper with a uniform film thickness can be obtained, and therefore a stamper with good transferability of fine patterns can be obtained. The industrial value is great.

[Brief explanation of drawings]

Figures 1 to 8 are schematic diagrams showing examples of anodes used in the electroforming apparatus of the present invention, Figure 9 is a schematic diagram showing the entire electroforming apparatus of the present invention, and Figure 10 is the film thickness of the obtained stamper. FIG. 3 is a graph diagram showing the relationship between the stamper radius and the stamper radius. 3.6.8, 10, 12, 23, 24: Anode 14: 1st
Anode 15: Second anode 7.9, 11, 13, 16
, 17: Notch 2: Cathode 5: Master Figure 4 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] A cathode that holds a master disc, an anode that is provided facing the master disc held by the cathode at a predetermined distance, and a cathode and anode that hold the master disc relative to each other while maintaining a predetermined interval. In the electroforming apparatus, the shape of the anode viewed from the direction of the axis of rotation of the rotary motion is such that a part of the outer periphery of the anode is inside the outer periphery of the master, and An electroforming device characterized in that the other part of the outer periphery of the anode is in a shape such that it is located at the same position as the outer periphery of the master or outside of it.