JP3279312B1 - Mold for molding and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a molding die for molding an optical recording medium, and more particularly to providing a molding die having a long life. SOLUTION: A stamper 4 mounting surface 1a on a surface of a cavity 3 of a movable mold 1 or a fixed mold 2 is provided on a surface 1a.
It is characterized in that a multilayer film 17 in which nitride films 18 and nitrogen-containing carbon films 19 are alternately laminated is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die,
CD (compact disk), DVD (digital
The present invention relates to a molding die for molding a versatile disk), a magneto-optical disk and the like, and more particularly, to provide a molding die having a long life and a method of manufacturing the same.

[0002]

2. Description of the Related Art As an apparatus for manufacturing a disk-shaped recording medium such as a CD or a DVD, a plastic is inserted into a mold cavity supporting a stamper, and the surface shape of the stamper is simultaneously transferred to a molded article by molding under pressure. This has been done in the past. FIG. 4 shows an example of such a molding die.

FIG. 4 is a sectional view showing the structure of a main part of a mold in a conventional molding machine. In this figure, 1 is a movable mold, 2 is a fixed mold, and 3 is a cavity formed in a mating surface of the two molds 1 and 2. A stamper 4 having a concavo-convex pattern such as a pre-group and a pre-pit formed on one side is attached to a facing surface (a stamper attaching surface) 1a. The stamper 4 is placed on the stamper mounting surface 1a of the movable mold 1, and its inner and outer peripheral portions are fixed to the movable mold 1 by stamper pressers 5a and 5b. In FIG. 4, reference numeral 6 denotes a resin supply port for introducing a molten substance from an injection molding machine (not shown) into the cavity 3, 7 a gate member, and 8 a gate for controlling the flow of the molten substance into the cavity 3. It is.

[0004] The movable mold 1 and the fixed mold 2 are formed of plastic molding steel, and at least the stamper mounting surface 1a of the movable mold 1 and the cavity of the fixed mold 2 are formed. The surface 2a is subjected to quenching and tempering or hard plating to improve hardness and wear resistance. Further, the stamper mounting surface 1a and the cavity surface 2a are finished in a mirror state, so that the dimensional accuracy of a product to be injection molded is improved.

The reason for polishing the movable mold 1 in this way is that the stamper 4 slides on the surface of the movable mold 1 due to expansion and contraction by heat. For example, if the temperature of the molten resin is 3
Assuming that the temperature of the movable mold 1 is 100 ° C. and the resin pressure is 400 kg / cm 2, the surface of the stamper 4 is 360 ° C.
The rear surface has a temperature of 100 ° C. and is pressed by the above pressure. Then, the stamper 4 moves along its surface by heat and pressure. For this reason, if molding is repeatedly performed using the above-described mold, the stamper 4 is damaged by shots due to friction, cracks are generated, and cracks are formed on the surface of the molded product. is there.

On the other hand, the stamper 4 is made of nickel, and the surface of the movable mold 1 which is in contact with the stamper mounting surface 1a is finished in a mirror state.

By the way, at the time of injection molding, the movable mold 1
Between the stamper mounting surface 1a and the stamper 4, the gas and fine solid impurities contained in the injected molten polymer substance (not shown) tend to enter. As is well known, at the time of injection molding of a polymer material, a high-temperature and high-pressure molten polymer material is injected into the cavity 3, and after the injection is completed, the polymer material injected into the cavity 3 is completely solidified. At this stage, a high-pressure press is applied to the cavity 3 in order to improve the homogeneity and transferability of the polymer substance.

However, in the conventional mold, since the hardness of the stamper mounting surface 1a of the movable mold 1 is not sufficiently high, the space between the stamper mounting surface 1a of the movable mold 1 and the back surface of the stamper 4 is limited. When the above-mentioned gas or solid impurities enter, not only the back surface of the stamper 4 but also the stamper mounting surface 1a of the movable mold 1 is locally peeled off by the action of the gas pressure and the polishing action of the solid impurities, so-called rough skin Is generated. Such a rough surface phenomenon causes a problem that the dimensional accuracy of the product is deteriorated.

The stamper 4 is a type in which the normal transferability of the concavo-convex pattern is impaired when thousands of optical recording media are duplicated, and the stamper 4 is sequentially replaced with a new stamper. Is enough. However, since the movable mold 1 and the fixed mold 2 are common devices used for each stamper to be sequentially replaced and are expensive devices, it is preferable that they have semi-permanent wear resistance.

[0010]

Therefore, in order to extend the service life of the mold and to provide a high-precision stamper, the stamper mounting surface of the mold is harder than the material constituting the stamper mounting surface. A hard layer made of a material having high wear resistance and excellent wear resistance, for example, TiN
There has been a solution that has been made by forming
No. 937), this technique can solve the problem to some extent, but does not provide sufficient wear resistance and low friction.

Therefore, as a technique for achieving abrasion resistance and low friction property, a molding die in which a diamond-like carbon thin film is coated on a stamper mounting surface of the die has been proposed (Japanese Patent Laid-Open No. 1-234214). ), There is an anxiety about the adhesion to the steel for the mold, and there is a problem in the durability.

The present invention has been made in view of the above point of view, and forms a cavity of a movable mold or a fixed mold in order to extend the service life of the mold and to provide a high-precision stamper. This problem has been solved by providing a molding die in which a multilayer film in which a nitride film and a nitrogen-containing carbon film are alternately laminated is provided on a portion supporting a stamper on the surface.

[0013]

Means for Solving the Problems The present invention comprises the following means 1) to 3 ) to solve the above problems. That is, 1) a multilayer film in which a nitride film and a nitrogen-containing carbon film are alternately laminated is provided on a stamper mounting surface of a surface forming a cavity of the movable mold or the fixed mold, and the nitride film and the nitrogen-containing carbon film are provided. The lamination cycle of the carbon film is 2 nm to 20 nm.
A molding die, characterized in that: 2 ) The nitride film is made of titanium nitride (TiN), silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), tantalum nitride (TaN), zirconium nitride (ZrN), or titanium aluminum nitride (TiAlN). 2. The molding die according to claim 1, wherein: 3 ) A method of manufacturing a molding die in which a multilayer film in which a nitride film and a nitrogen-containing carbon film are alternately laminated is provided on a stamper mounting surface of a surface forming a cavity of a movable mold or a fixed mold. The nitride film and the nitrogen-containing carbon film provided on the stamper mounting surface of the surface constituting the cavity are:
Manufacturing the molding die, wherein the molding die is formed by depositing on the stamper mounting surface by reactive sputtering while placing and rotating the molding die on a substrate holder in a vacuum film forming chamber. Method.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. It should be noted that since the following examples are preferred specific examples of the present invention, various technically preferable limitations are added. However, the scope of the present invention is particularly limited in the following description. Are not limited to these embodiments unless otherwise described.

FIG. 1 is an explanatory view of a film forming apparatus for forming a multilayer film provided on a stamper mounting surface of a movable mold constituting a molding mold according to the present embodiment, and FIG. FIG. 3 is a side view showing a configuration example of a film, and FIG. 3 is another side view showing a configuration example of a multilayer film.

FIG. 1 is an explanatory view of a film forming apparatus for forming a multilayer film provided on a stamper mounting surface of a movable mold. In FIG. 1, reference numeral 10 denotes a vacuum film forming chamber;
Is a substrate mounted on the surface of a disk-shaped substrate holder 11 arranged in the vacuum film forming chamber 10. Note that 11
a is the axis of the substrate holder 11 described above, and this axis 11
a is rotatable by means not shown.

Reference numerals 13a and 13b denote two types of targets, which will be described later, disposed in the vacuum film forming chamber 10 so as to face the substrate 12, and reference numerals 14a and 14b denote power supplies for the respective targets 13a and 13b. It is. Also,
Reference numeral 15 denotes a high vacuum evacuation system which is composed of a turbo molecular pump and a rotary pump and is connected to the above-described vacuum film formation chamber 10. The vacuum film formation chamber 10 is controlled to about 10 ⁻⁶ Torr by the high vacuum evacuation system 15. It is evacuated to a high vacuum up to. Reference numerals 16a and 16b denote mass flow controllers which are connected to the vacuum film forming chamber 10 and control the flow rates of argon gas and nitrogen gas, respectively.

Next, a film forming method for forming a multilayer film using the film forming apparatus shown in FIG. 1 will be described in detail. First, the inside of the vacuum film forming chamber 10 is evacuated to a high vacuum state of about 10 ⁻⁶ Torr by the high vacuum evacuation system 15 composed of the turbo molecular pump and the rotary pump. The temperature of the substrate 12 is adjusted to a predetermined temperature by a heater (not shown) built therein.

The reason why the high vacuum state is set in this way is to increase the degree of vacuum in the vacuum film forming chamber 10 to eliminate impurity gases and improve the film forming quality.

Next, a constant flow of argon gas (sputter gas) is introduced by the mass flow controller 16a. Next, a constant flow rate of reaction gas nitrogen is introduced by the mass flow controller 16b, and the substrate holder 11 is rotated at a predetermined speed.

On the other hand, the above-mentioned power sources 14a and 14b excite the above-mentioned sputtering gas into plasma, and the titanium (T
A titanium nitride (TiN) film and a nitrogen-containing carbon (CN) film are laminated at a lamination cycle from particles sputtered out of each of the targets i) and graphite 13a, 13b to form a multilayer film.

FIG. 2 is a side view showing a configuration example of a multilayer film formed by the above-described film forming method, and FIG. 3 is another side view showing the same configuration example of the multilayer film. , 17 is a multilayer film, 18 is a nitride film, 19 is a nitrogen-containing carbon film, 2
0 is a lamination cycle. The lamination cycle 20 is 2n
A range from m to 20 nm is preferred. Because 2n
If it is less than m, the productivity is poor, and the hardness of the obtained surface is not as high as the desired hardness due to the bonding between the layers. This is because a desired product cannot be obtained in terms of hardness.

As described above, the multilayer film 17 shown in FIG.
First and second layers 18 and 19 having different compositions from each other
A plurality of lamination cycles 20 composed of
The stamper mounting surface 1a is sequentially stacked on the stamper mounting surface 1a.
It is formed over the whole, so that the individual properties of the laminated unit can be utilized.

The multilayer film 17 shown in FIG. 3 is formed by laminating the first and second layers in a manner reverse to that shown in FIG. 2, so that the individual properties of the lamination unit can be utilized. It is.

It is preferable that the outermost layer of the multilayer film 17 be a nitrogen-containing carbon film because low friction property can be easily obtained.

The multilayer film formed by the reactive sputtering method according to this embodiment is suitable for freely adjusting the thickness of each layer. However, the multilayer film may be formed by other vapor deposition methods, for example, a cathodic arc method, vacuum vapor deposition, ion plating, a plasma enhanced chemical vapor deposition method, and the like, and is not necessarily limited to this embodiment. Not something.

Further, the formed multilayer film has the effects described in the present description regardless of whether the interface between the layers is flat or non-planar. Further, even when the layers are mixed at the time of deposition and the roughness of the interface becomes considerably large, the same effect can be sufficiently expected.

(Embodiment 1) Hereinafter, this embodiment will be described with reference to FIGS. The same parts as those in the related art are denoted by the same reference numerals, and detailed description thereof will be omitted. First, a high vacuum evacuation system 15 composed of the above-mentioned turbo molecular pump and rotary pump
As a result, the inside of the vacuum film forming chamber 10 is evacuated to a high vacuum state of about 10 ⁻⁶ Torr.

Next, the movable side mold 1 whose surface is mirror-finished
1 is disposed at a predetermined position in the vacuum film forming chamber 10 in FIG. 1, and the stamper mounting surface 1a on the cavity side in FIG. 4 is used as the substrate 12, and argon (Ar) as a sputtering gas is provided in the vacuum film forming chamber 10 in FIG. ) A gas and a nitrogen (N ₂ ) gas as a reaction gas are continuously introduced while adjusting the inflow amount by a mass flow controller so that the inside of the vacuum film forming chamber 10 is brought into a high vacuum state of about 10 ⁻³ Torr. Exhaust.

Next, a film having a lamination cycle of 4 nm and a thickness of 2 μm was formed at a temperature of the substrate 12 of 200 ° C., a sputtering power of 1500 W for a titanium (Ti) target and 700 W for a graphite target.

The obtained mold was assembled in an injection molding machine for a CD shown in FIG. 4, for example, to perform molding. For comparison, injection molding was similarly performed on TiN-coated ones according to the conventional method, and the results as shown in FIG. 5 were obtained.

As can be seen from FIG. 5, the molding die according to the present embodiment uses a multilayer film in which a nitride film and a nitrogen-containing carbon film are alternately laminated as a stamper supporting surface, thereby achieving a long mold life. Could be greatly extended.

In this embodiment, an example in which titanium nitride (TiN) is used as the nitride film has been described. However, silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), tantalum nitride Ride (T
aN), zirconium nitride (ZrN) or titanium aluminum nitride (TiAlN) can provide the same effect.

[0034]

According to the first and second aspects of the present invention, the abrasion resistance, corrosion resistance and / or low frictional property are greatly improved, whereby the durability of the stamper supported on the cavity surface of the molding die is improved. The number of years is greatly improved. According to a third aspect of the present invention, the nitride film and the nitrogen-containing carbon film provided on the stamper mounting surface on the surface of the cavity of the molding die according to the first and second aspects are formed by vacuuming the molding die. Since it is a method of manufacturing a molding die formed by depositing on the stamper mounting surface by reactive sputtering while being mounted on a substrate holder in a film forming chamber and rotating, wear resistance, corrosion resistance, And / or a molding die with significantly improved low friction properties.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a film forming apparatus for forming a multilayer film provided on a stamper mounting surface of a movable mold constituting a molding mold according to the present invention.

FIG. 2 is a side view showing a configuration example of a multilayer film.

FIG. 3 is another side view showing a configuration example of the multilayer film.

FIG. 4 is a cross-sectional view of a conventional molding die.

FIG. 5 is an explanatory view showing a comparison of a stamper between the present invention and a conventional example, which are injection molded by a molding die.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 movable mold 1a stamper mounting surface 2 fixed mold 2a cavity surface 3 cavity 4 stamper 5a stamper inner peripheral pressing member 5b stamper outer peripheral pressing member 6 resin supply port 7 gate member 8 gate 10 vacuum film forming chamber 11 substrate Holder 11a Axis 12 Substrate 13a, 13b Target 14a, 14b Power supply 15 High vacuum exhaust system 16a, 16b Mass flow controller 17 Multilayer film 18 Nitride film 19 Nitrogen-containing carbon film 20 Stacking cycle

Claims (3)

(57) [Claims] 1. A multilayer film in which a nitride film and a nitrogen-containing carbon film are alternately laminated on a stamper mounting surface of a surface forming a cavity of a movable-side mold or a fixed-side mold. A molding die, wherein the lamination cycle of the carbon film is 2 nm to 20 nm. 2. A nitride film comprising titanium nitride (Ti)
N), silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), tantalum nitride (T
The molding die according to claim 1, wherein the molding die is aN), zirconium nitride (ZrN) or titanium aluminum nitride (TiAlN). 3. Production of a molding die in which a multilayer film in which a nitride film and a nitrogen-containing carbon film are alternately laminated is provided on a stamper mounting surface of a surface constituting a cavity of a movable mold or a fixed mold. In the method, the nitride film and the nitrogen-containing carbon film provided on the stamper mounting surface of the surface constituting the cavity are formed by a reactive sputtering method while rotating the molding die placed on a substrate holder in a vacuum film forming chamber. The method of manufacturing a molding die, wherein the molding is formed by depositing on the stamper mounting surface.