JPS5920486A - Manufacture of metallic mold for precision molding - Google Patents

Abstract

PURPOSE:To manufacture the titled metallic mold having unevenness transferred accurately from a matrix and high surface hardness, by depositing a hard film on the surface of the matrix by a vacuum deposition method, depositing a metal on the hard film by electroforming, and stripping the matrix from the hard film. CONSTITUTION:A matrix 1 is treated with an inverse current in an aqueous NaOH soln. to form a stripping accelerating layer 2. A hard film 3 such as a Cr film is deposited on the layer 2 by a vacuum deposition method. After etching the surface of the film 3, an Ni layer 4 is formed by striking, and an Ni layer 5 of the required thickness is further deposited on the layer 4 by electroforming. After finishing the formation of the layer 5, the matrix 1 including the layer 2 is stripped from the film 3 to obtain a stamper 6.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing a mold by transferring from an I mold.

[Technical background of the invention and its problems] Conventionally, in order to manufacture information recording discs such as video discs,
First, a recording signal and the like are recorded in a concave and convex shape using a laser beam on a glass master disk coated with photoresist to form a master disk. From this master disc, a master, mother, and stamper are successively created by nickel plating or copper plating. Then, using Stannosy as a mold, the four-electrode force-bon particles dispersed in the molding composition were compression-molded to produce a capacitance type recording disk. The molding composition contains abrasive particles such as heavy metals and carbon particles, and when compression molding is performed using the stamper, these abrasive particles cause scratches on the stamper surface. There is a problem in that these scratches are transferred onto the next recording disc, resulting in an inconvenient "faulty defect" during playback of the recording disc.

To solve this problem, the stamper surface is usually
．． Chrome plating of around 1 [μm] is applied to protect the nuclear surface. In addition, in JP-A-56-34430, a thin film containing chromium was applied to improve the unevenness of the mother mold surface.
It has been proposed to improve the scratch resistance of the stamper by adhering it to the surface of the stamper on which f4K has been transferred.

However, when a hard film is applied to the stamper surface, which accurately transfers the unevenness of the mother mold surface, accurate transfer of signals is significantly hindered. Furthermore, with a chrome plating thickness of around 0.1 [1 lIn], it is impossible to obtain the hardness inherent in chrome plating.

Therefore, in JP-A-49-103846, hard alloy plating was applied, and in JP-A-50-23453, nickel-boron plating was applied.
After forming alloy plating on the surface of each mother mold, the mold body is electroformed on the alloy plating layer, and the υ mold is formed by peeling between the alloy plating layer and the mother mold. A manufacturing method has been proposed.

However, the surface of the stamper obtained by these methods, that is, the alloy layer, has the disadvantage that it is easily contaminated by the stabilizer contained in the molding composition.

Therefore, the stamper can be used without impairing signal transferability.
It is desired to realize a method of increasing surface hardness. In addition, this method has been established not only for video disc stampers, but also in the field of manufacturing other precision molds that require surface hardening. This method was developed to solve the problem, and the method for manufacturing a mold for sheath-dense molding is such that the unevenness on the surface of the precision molding mold accurately transfers the unevenness on the Rh mold, and the surface hardness is made uniform. The purpose is to provide

[Summary of the invention] This invention involves depositing a hard film on the surface of the mother mold using an air vapor deposition method when manufacturing a mold by transfer, and then electroforming -C metal onto the hard film. In this method, the matrix is thickened and peeled from the hard film.

[Effects of the Invention] According to the present invention, since the hard film of C is deposited on the surface of the matrix in advance by vacuum evaporation, the unevenness of the surface of the matrix is transferred to the bell, and the surface hardness is high. Kokichi, which manufactures molds, is established. Therefore, when applied to the production of stampers for video discs, it is possible to minimize the occurrence of scratches caused by abrasive particles in the molding composition. Additionally, chromium, molybdenum, and tungsten are all less susceptible to contamination by stabilizers in molding compositions. Therefore, the life of the stamper can be significantly extended due to the above modification.

In addition, in the vacuum deposition method, since the film thickness distribution can be adjusted more easily than in the wet plating method, a uniform hard film can be formed with good reproducibility, making it extremely useful.

[Embodiments of the invention] The present invention will be described in detail below with reference to the drawings.

1 to 4 are cross-sectional views showing the process of manufacturing a precision molding die by transfer from a mother die according to the present invention. First, as shown in FIG. From the surface layer to the inside over the number ]0 (X, ], 5% N
The peel-promoting layer 2 was formed by reverse current treatment in an aOH aqueous solution at 0°C and a bath voltage of 5V.

Next, as shown in Fig. 2, this mother l was placed in a vacuum evaporation apparatus, and 99.9% chromium was deposited in granular form on a tungsten boat in a vacuum of 1O-5 (TorrJ).
Sublimated at 0 [C] to a thickness of 1. A chromium film (hard film) 3 of Q (It m) was deposited.

The surface of the chromium film formed as described above was exposed to a stainless steel cathode at 7 [v] and 6Q (s) in a mixed solution of 95 volumes of ethanol and 5 volumes of hydrochloric acid (specific gravity 1.18).
After etching under the conditions of
), cathode current density 10 (A/d+n2) , , l
A nickel strike plating layer 4 was formed at a plating time of 5 min (FIG. 3).

Composition of plating bath for nickel strike: Furthermore, sulfur amino acids were added to the nickel strike plating layer 4 using a plating bath with the following composition under the conditions of 50 ('O), cathode current density of 5 (&am2), and pH of 4. Nickel plating was applied, and a nickel electroformed layer 5 of the required thickness was filled (Fig. 3).

Nickel sulfamate plating bath composition: Nickel sulfamino acid 450 (Il) Nickel' After the formation of the second cast layer 5, the chromium layer 3 and the mother l (peeling promotion layer 2)
) to obtain a stamper 6 as shown in FIG.

Table 1 shows the surface hardness and film thickness of the stamper obtained by the above method. In addition, as Comparative Example 1, the surface of Mother I was treated to promote peeling, and then electrolytic nickel plating was performed in a sulfur amino acid nickel bath under the same conditions as before to form a nickel electroformed layer. Peel it off from the mother and use it as a stamper. As Comparative Example 2, the stamper obtained in Comparative Example 1 was immersed in a plating bath having the following composition.
Q) Electrolytic chromium plating was performed under the conditions of cathode current density of 30 (A/dm2) to deposit chromium with a thickness of 0.1 (z1 m').

The surface hardness and film thickness of the stampers obtained in Comparative Examples 1 and 2 are shown in Table 1 as in the Examples.

Margin below From this Table 1, the hardness is compared to Comparative Example 1 v/ll
2 i 1.4 to 1.8 times, actual mli example c3.7
~4.6 Doubling j) rJ L, you will know that you are lucky.

Furthermore, in the stampers obtained in Examples, Comparative Example 1, and Comparative Example 2, the diameter of the central pattern around 100 (mm) was
- The measured values of the tee ratio are shown in Table 2.

The T-T ratio is high in Comparative Example 2, which uses a method of applying rim) on the stamper surface, but Example and Comparative Example 1 show 49%, which is close to (3). It can be seen that the recording and transfer properties are excellent. As described above, according to the method of the present embodiment, if the signal reproduction characteristics resulting from the recording transfer property are reduced (!), the hardness of the stamper can be increased. The present invention is not limited to this, and various modifications can be made.

For example, various conditions, film thickness, etc. for the vacuum evaporation method can be changed as appropriate. Furthermore, the hard film is not limited to chromium, but may also be tungsten or molybdenum. Furthermore, the present invention is applicable not only to stampers for video discs, but also to various precision molds that require surface hardening.

[Brief explanation of the drawing]

FIGS. 1 to 4 are diagrams showing the method for manufacturing a mold according to the present invention in the order of manufacturing steps. l...Mother, 2...Peeling promotion layer, 3...Chromium vapor deposited film (hard film), 4...Nickel strike plating layer,

Claims (2)

[Claims] (1) When manufacturing the υ mold by transfer, a hard film is applied to the surface of the L mold using a vacuum evaporation method, and then a metal is applied on the hard film by electroforming, and then the A method for manufacturing a precision molding mold having a hard film on the surface of the mold, characterized in that the mother mold is peeled off from the hard film. (2) A method for producing the hard film, including chromium and molybdenum.