JPH0624728B2 - Method for manufacturing duplicate mold for precision molding - Google Patents

Description

The present invention relates to a method of manufacturing a duplicate mold for precision molding called a stamper for molding a duplicate substrate of an information recording board on which various information signals are recorded, In particular, the present invention relates to a method for producing a precision molding duplicate mold capable of efficiently smoothing the back surface of the stamper, which serves as a mounting surface when the stamper is mounted on a die for press or injection molding.

[Conventional technology]

For example, a stamper used for molding a record board in which audio signals are engraved in a spiral shape or a substrate (generally a plastic substrate) such as an optical disc or a compact disc whose information recording density is several hundred times higher than that of a record disc is Generally, it is manufactured as follows.

First, the surface of the master (usually made of glass) on which information signals are recorded is made conductive by silver mirror, electroless plating, vapor deposition, etc., and then nickel is electrodeposited to a thickness of about 0.3 mm by electroforming. . After that, the electrodeposited plate is peeled off from the master to form a first duplicate mold generally called a master. Further, the master is dipped in a potassium dichromate solution or the like to form a coating film on the surface of the master that is easy to peel off, and then nickel is electrodeposited again by electroforming to the same thickness as the master. For this electroforming, a sulfamine bath is generally used because of the relationship between the electrodeposition stress and the deposition rate. After that, the electrodeposited plate is separated from the master to form a second mold generally called a mother. Further, the same means as making a mother from a master is repeated to form a new electrodeposition plate, and a duplicate mold for precision molding generally called a stamper is made. FIG. 2 shows an example of a conventional stamper 1.

The stamper thus created is attached to a pressing die or an injection molding die, and a molding composition, for example, a resin such as vinyl chloride, acryl, or polycarbonate, is injected or pressed into the die to press the optical disc or compact disc. To make a duplicate substrate.

By the way, with the development of information equipment, recently, there is a strong demand for higher precision of the substrate, and it is possible to prevent scratches at the time of adhesion or peeling of the rubber when the mother or stamper is created from increasing defects of the substrate. For this reason, a master is often called a master stamper and used for molding the substrate.

As can be seen from the manufacturing method of such a stamper, the irregularities on the back surface of the stamper to which the information signal of the master has been transferred are usually projected on the front surface, and this is used as it is for a mold for injection molding or press molding. Since the surface of the stamper will be distorted and the accurate substrate cannot be obtained if the substrate is molded by mounting it on the surface of the stamper, smooth the back surface of the stamper, that is, the die mounting surface of the stamper to the order of 1 μm or less Is generally practiced. The smoothing of the die mounting surface of such a stamper is performed by peeling the master from the master and then attaching the stamper to a smooth glass plate or metal plate using an adhesive or double-sided tape, and then lathe. It is common to cut with a cutting machine of. Of course, it is also possible to cut the stamper as it is without using a smooth plate such as the above glass plate or metal plate.

However, the nickel electrodeposited material constituting the stamper has a relatively low Vickers hardness (Hv) of about 200 to 300, and is difficult to cut because nickel has large malleability and stickiness. That is, it is often difficult to obtain a uniform cutting surface due to the fact that a diamond tool or a carbide tool used for cutting bites into the cutting surface or partially cuts during cutting. There is a drawback that productivity is poor because a cutting time of about 1 to 5 hours is required to finish the roughness of the die mounting surface to about 1 μm or less. Further, since the malleability and stickiness are large, the diamond bite and the carbide bite are significantly worn, and it is necessary to replace the bite several times before finishing the die mounting surface.

[Problems to be solved by the invention]

The present invention has been made in view of the above points, and an object of the present invention is to solve the problems in the method for producing a duplicate mold for precision molding of the conventional example described above, and to provide a plurality of precision molding dies. Duplicate mold for precision molding capable of easily smoothing the die mounting surface of the mold, and capable of producing with high productivity a duplicate mold for precision molding having a mold mounting surface with good plane accuracy It is to provide a manufacturing method of.

[Means for solving problems]

The above object of the present invention is achieved by the following present invention.

When manufacturing a nickel precision molding duplicate mold for molding a duplicate substrate for reproducing the information signal recorded on the master, electroless nickel alloy plating or electric is applied to the mold mounting surface of the precision molding duplicate mold. A method of manufacturing a precision molding duplicate mold, comprising the steps of forming a plating layer by nickel alloy plating and cutting the plating layer to smooth the mold attachment surface of the precision molding duplicate mold. .

[Work]

In the method of the present invention, a plating layer of a nickel alloy having a hardness higher than that of nickel and excellent in machinability is formed on the die mounting surface of the stamper, and the plating layer is used as the die mounting surface of the stamper to perform cutting smoothing. Therefore, without causing the difficulty of cutting the die mounting surface as in the stamper of the conventional example which is difficult to cut due to the large malleability and stickiness,
It is possible to manufacture a stamper having a die mounting surface with good plane accuracy with high productivity. Further, the rigidity of the stamper can be improved by forming a plating layer.

In the basic aspect of the present invention, first, the electrodeposition plate 2 made of nickel corresponding to the conventional stamper as illustrated in FIG. 1 is formed by the above-described known stamper forming method.

Next, a plating layer 3 is formed by electroless nickel alloy plating or electric nickel alloy plating on the side of the electrodeposition plate 2 which will be the die mounting surface. Examples of the nickel alloy constituting the plating layer 3 include Ni-P, Ni-B, Ni-BW, and Ni-Co alloys.

Next, the stamper 1 having the plating layer 3 thus created is mounted on a known cutting device such as a lathe type mirror finishing machine so that the plating layer 3 faces the cutting member such as a diamond bite or a cemented carbide bite. To cut. At this time, the cutting may be performed by attaching the stamper to the smooth plate as described above, or may be performed without particularly mounting the smooth plate.

〔Example〕

 Examples of the present invention will be shown below.

Example 1 500 to 10 of nickel was put on a glass master recording an information signal.
After vapor-depositing to a thickness of 00Å to make it conductive, nickel was electro-deposited thereon to a thickness of about 0.27 mm to form a master stamper.

Next, in a state where nickel was electrodeposited on the glass master plate of this master stamper, a commercially available Ni-P electroless plating solution (manufactured by Okuno Seiyaku Co., Ltd .; trade name; Toppnicol N-
It is immersed in 47) and plated for 2 hours with occasional rocking, and the thickness of 40 μm is attached to the die mounting surface of this master stamper.
m plating layer was formed. The thickness of the master stamper after plating was 0.31 mm.

The master stamper thus formed with the plating layer was mounted on the cutting jig spindle side of a lathe type mirror finishing machine so that the die mounting surface could be cut, and cutting was performed using a diamond bite. At the time of cutting, cutting oil is used, the rotation speed of the lathe type mirror finishing machine is 2200 rpm, and the blade feed is 0.
It was performed at 01 mm / rev and a stock removal of 5 μm.

When the cutting was carried out in this way, a stamper having a die mounting surface with good smoothness and a roughness of the cutting surface of Rmax of 0.1 μm could be obtained in a cutting time of 15 minutes. At this time, the exchange of bytes was not particularly necessary.

Example 2 A mother prepared from a glass master recording information signals was immersed in a 0.1-3% aqueous solution of potassium dichromate for 1 to 3 minutes, and then nickel was electroplated thereon to a thickness of 0.29 mm by electroforming. did.

Next, the electrodeposit was peeled from the mother, and a heat- and chemical-resistant masking coating agent for plating (made by Kakohki Shoji Co., Ltd., trade name; Turco 51
45) was applied to a thickness of 0.3 to 0.5 mm.

Next, the masked electrodeposit was immersed in a commercially available Ni-BW electroless plating solution (manufactured by World Metal Co., trade name; Nivofram) heated to 60 to 70 ° C, and plated for 3 hours with occasional shaking. The Ni-B on the die mounting surface.
A stamper having a 20 μm thick plating layer made of a -W alloy was obtained. The thickness of this stamper was 0.31 mm.

After a glass plate was attached to the information recording surface side of the stamper thus obtained using a double-sided tape, this was applied to Example 1
It was attached to the same lathe-type mirror finishing machine as in Example 1 and cut under the same cutting conditions as in Example 1.

When the cutting was carried out in this way, a stamper having a die mounting surface with good smoothness and a roughness of the cutting surface of Rmax of 0.1 μm could be obtained in a cutting time of 15 minutes. At this time, the exchange of bytes was not particularly necessary.

〔The invention's effect〕

As described above, according to the present invention, it is easy to smooth the die mounting surface, and a method for producing a duplicate mold for precision molding with high productivity in which the cutting time is shortened to about 1/20 of the conventional method. It came to be offered. Furthermore, it has become possible to reduce bite wear during cutting.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example of a stamper according to the present invention,
FIG. 2 is a schematic sectional view of an example of a conventional stamper. 1 ... Stamper, 2 ... Electroplated plate 3 ... Plating layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G11B 3/70 7525-5D 7/26 7215-5D

Claims (2)

[Claims] 1. When manufacturing a nickel precision molding duplicate mold for molding a duplicate substrate for reproducing an information signal recorded on a master, electroless is applied to a mold mounting surface of the precision molding duplicate mold. A precision molding duplication comprising a step of forming a plating layer by nickel alloy plating or electric nickel alloy plating, and cutting the plating layer to smooth the die mounting surface of the precision molding duplication die. Mold manufacturing method. 2. The duplicate mold for precision molding according to claim 1, wherein the nickel alloy is a Ni-P, Ni-B, Ni-BW or Ni-Co alloy. Production method.