JPH07109668B2 - 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 to mold 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 in which audio signals are engraved in a spiral shape or 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. To do. 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, recently, with the development of information equipment, there is a strong demand for higher precision of the substrate, and it is possible to prevent the defects of the substrate from increasing due to scratches at the time of dust attachment or peeling when creating the mother or stamper. 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 polishing plate. It is common to polish with an abrasive. Of course, it is also possible to polish 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 polish because nickel has large malleability and stickiness. That is, it is often difficult to obtain a uniform polished surface because the abrasive grains are eroded into the polished surface during polishing or are partially scraped off. Therefore, the roughness of the die mounting surface of the stamper can be reduced to 1 by polishing.
A polishing time of about 5 to 10 hours is required to finish to a size of about μm or less, and there is a drawback that productivity is poor.

[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 precision molding replication mold of the conventional example described above, and to provide a precision molding replication mold. 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 that reproduces the information signal recorded on the master disc, a Ni-
P, Ni-B, Ni-BW or Ni-Co type electroless nickel alloy plating or electroless nickel alloy plating is used to form a plating layer and the plating layer is polished to attach the duplicate mold for precision molding. A method for producing a duplicate mold for precision molding, comprising the step of smoothing a surface.

[Action]

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 polishing property 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 smoothing and polishing. Therefore, without causing the difficulty of polishing the die mounting surface as in the conventional stamper, which has large malleability and stickiness and is difficult to polish,
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 forming 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 prepared is placed in a known polishing machine having, for example, a polishing dish and a work fixing base so that the plating layer 3 faces the polishing dish side and polishing is performed. At this time, the polishing may be performed by attaching the stamper to the smooth plate, or may be performed without attaching the smooth plate.

〔Example〕

 Examples of the present invention will be shown below.

Example 1 Nickel 500 to 100 on a glass master recording an information signal.
After vapor-depositing to a thickness of 0Å 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 with the plated layer thus formed was attached to a polishing machine so that the die mounting surface could be polished, and the polishing pressure was 0.03 kg / cm ² using aluminum oxide as the polishing agent.
And sometimes 0.30 while measuring the thickness of the master stamper
Polishing was performed until the thickness became mm.

As a result of polishing in this way, it was possible to obtain a stamper having a die attachment surface with good smoothness and a roughness of the polished surface of 0.02 μm in a polishing time of 0.5 to 2.5 hours.

Example 2 A mother prepared from a glass master recording an information signal was immersed in a 0.1-3% aqueous solution of potassium dichromate for 1 to 3 minutes, and then nickel was electro-deposited 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 polishing machine as above, and was polished to a thickness of 0.30 mm while measuring the thickness of the master stamper at a polishing pressure of 0.03 kg / cm ² with aluminum oxide as the polishing agent.

As a result of polishing in this way, it was possible to obtain a stamper having a die attachment surface with good smoothness and a roughness of the polished surface of 0.02 μm in a polishing time of 0.5 to 2.5 hours.

〔The invention's effect〕

As described above, according to the present invention, the mold mounting surface can be easily smoothed, and the polishing time is shortened to about 1/10 to 1/2 of that of the conventional method, which is a highly productive duplicate mold for precision molding. The manufacturing method of can be provided.

[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

Claims (1)

[Claims] 1. When manufacturing a nickel precision molding duplicate mold for molding a duplicate substrate for reproducing an information signal recorded on a master, Ni is attached to a mold mounting surface of the precision molding duplicate mold. -P, Ni-B, Ni-BW or Ni-Co type electroless nickel alloy plating or electroless nickel alloy plating to form a plating layer, and polishing the plating layer to mold the duplicate mold for precision molding A method of manufacturing a duplicate mold for precision molding, comprising the step of smoothing a mounting surface.