JPH0223526A - Production of thin metallic film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a metal thin film, which involves continuously forming a metal thin film on a polyimide film.

Conventional technology Conventionally, methods for continuously forming metal thin films include plating methods, sputtering methods, and vacuum evaporation methods (including methods that deposit films by ionizing some of the evaporated atoms, such as ion-blating methods). ) etc. In particular, vacuum evaporation can achieve a high deposition rate and is suitable for mass production.

As a method for manufacturing a metal thin film using a polyimide film by a vacuum evaporation method, the most excellent method is to evaporate the metal thin film while moving the substrate along the circumferential surface of a cylindrical can. When forming a metal thin film on a polyimide film at a high deposition rate using such a method, thermal deformation and thermal decomposition of the polyimide film may occur due to causes such as radiant heat from the evaporation source and condensation heat of evaporated atoms. It is difficult to form a stable metal thin film due to heat loss. Therefore, when forming a metal thin film at a high deposition rate, it is necessary to take some measures to avoid these thermal damages.

Therefore, in order to prevent heat loss, it is necessary to firmly attach the polyimide film to the circumferential surface of the cylindrical can so that the heat received by the polyimide film can be efficiently released to the cylindrical can body. One method of attaching a polyimide film to the circumferential surface of a cylindrical can is to create a potential difference between the metal thin film formed on the polyimide film and the cylindrical can, and utilize the electrostatic attraction that acts between them ( According to this method (Japanese Patent Application No. 56-190001), it is possible to form a single layer or multilayer metal thin film on a polyimide film. FIG. 2 is a front view schematically showing the internal structure of a vacuum evaporation apparatus using such a method. The polyimide film 1 is unwound from the supply roll 3, passes through the free roller 6, and runs along the circumferential surface of the cylindrical can 2 in the direction of the arrow. In addition, cylindrical can 2
The peripheral surface of is generally plated with hard Cr.

A metal thin film is formed on this polyimide film 1 by an evaporation source 5. A shielding plate 9 is arranged between the evaporation source 5 and the cylindrical can 2 in order to prevent the vapor evaporated from the evaporation source 5 from adhering to unnecessary parts. The shielding plate 9 has a frontage as shown by S, and this opening S
The vapor that has passed through is deposited on the polyimide film 1.

The metal thin film formed on the polyimide film 1 passes through a free roller 7 and is wound onto a winding roll 4. A voltage is applied between the free roller 7 and the cylindrical can 2 by a power source 8. Although the power source 8 is shown as a DC power source, it may be an AC power source.A potential difference is created between the metal thin film on the polyimide film 1 and the cylindrical can 2 via the free roller 7, and the metal thin film on the polyimide film 1 is heated. The formed portion is stuck to the circumferential surface of the cylindrical can 2.

Problems to be Solved by the Invention However, when forming such a metal thin film, a potential difference is created between the metal thin film on the polyimide film 1 and the cylindrical can 2, and the portion of the polyimide film l where the metal thin film is formed is When the polyimide film 1 is attached to the circumferential surface of the cylindrical can 2, the back surface of the polyimide film 1 is charged. When the polyimide film 1 is charged, the running of the polyimide film 1 becomes unstable, and it is difficult to manufacture a long metal thin film without wrinkles.

An object of the present invention is to provide a method for manufacturing a metal thin film that solves the problems of the prior art.

Means for Solving rRB The present invention provides a method for forming a thin metal film by vacuum evaporation on a polyimide film running along the circumferential surface of a cylindrical can. is Ni, and the metal thin film manufacturing method provides a potential difference between the cylindrical can and the metal thin film.

According to the present invention, when forming a metal thin film, a potential difference is created between the metal thin film on the polyimide film and the cylindrical can, and the portion of the polyimide film where the metal thin film is formed is placed on the circumferential surface of the cylindrical can. Even when pasted, the back side of the polyimide film does not become charged.

Embodiments Below, embodiments of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows a part of the cross section of a cylindrical can used in the present invention, which is a cylindrical can with a Ni layer 21 on the circumferential surface of the cylindrical can body 20. The material constituting the circumferential surface of the can main body 200 is usually determined based on mechanical requirements such as hardness, workability, or polishability, and is generally hard Cr formed by a plating method. Since N1 is somewhat insufficient in terms of mechanical properties as a constituent material for the circumferential surface, a structure having N1Fi21 on the circumferential surface of the cylindrical can body 20 is adopted.
It is necessary to reinforce the i-layer 21. As a method for forming the N1 layer, a plating method, a sputtering method, or a vapor deposition method is preferable.

Next, a specific example will be described in which a Co--Cr film is selected as the metal thin film. In addition, Co-Cr1
11 is attracting attention as a magnetic recording medium capable of high-density recording.

Example 1 A cylindrical can 2 as shown in FIG. 1 was applied to a vacuum evaporation apparatus as shown in FIG. 2, and a 250 nm thick Co -
A Cr film was formed. The film deposition rate during formation of the Co--Cr film was 600 nm/sec.

At the time of forming the Co--Cr film, a potential difference of 200 μ was provided between the Co--Cr film and the cylindrical can 2. The N1 layer 21 was formed by a vapor deposition method. The thickness of the Ni layer was 50 μm. Polyimide film runs stably without being charged, and is free of Co
-The Cr film could be formed over a long length without wrinkles.

Here, the charging of the back surface of the polyimide film 1, which is a problem in the present invention, will be explained.

The charging on the back surface of the polyimide film 1, which is a problem in the present invention, is considered to be called contact charging.

Contact charging occurs when two materials are brought into contact, and as a result of the exchange of electrons between the two materials at the contact surface. Which of the two types of substances gives out electrons and which receives them is determined by the number of work done by the substances. Of the two substances, the one with a smaller work function gives out electrons and becomes positively charged, and the one with a larger work function receives electrons and becomes negatively charged. When the substance is a metal, its work function can be measured relatively easily using the photoelectric effect, but it is difficult to measure the work function of a semiconductor or especially an insulator.

Since the charge on the back side of the polyimide film in the conventional example is negative, it is thought that the effective work function of the polyimide film is larger than that of Cr and the polyimide film.In the case of the present invention, the effective work function is We believe that the results were about the same for polyimide film and Ni. Therefore, when using a film other than a polyimide film, it is considered that the present invention can be applied as long as there is a material suitable for the film.

Incidentally, even in the conventional example, simply running the polyimide film 1 along the circumferential surface of the cylindrical can 2 does not result in much charging. It is thought that the polyimide film 1 is strongly attached to the circumferential surface of the cylindrical can 2 in a high temperature state, and the actual contact area becomes large, resulting in a strong charge.

In the above embodiments, only a single-layer Co--Cr film was described as the metal thin film, but it is clear that the present invention is also effective with single-layer or multi-layer metal thin films made of other metal materials.

Effects of the Invention As is clear from the above description, according to the present invention, when forming a metal thin film, a potential difference is provided between the metal thin film on the polyimide film and the cylindrical can, and the metal thin film on the polyimide film is heated. Even if the formed part is strongly attached to the circumferential surface of a cylindrical can, the back side of the polyimide film will not be charged, and the running of the polyimide film will become stable. It is possible to produce thin films.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a part of the cross section of a cylindrical can used in a method for manufacturing a metal thin film in one embodiment of the present invention, and FIG. 2 is a schematic diagram of the internal structure of a vacuum evaporation apparatus in the same embodiment. FIG. 1... Polyimide film, 2... Cylindrical can,
3... Supply roll, 4... Take-up roll, 5...
・Evaporation source, 6.7・轡・Free roller 8...Power source, 9...Shielding plate, 20...Cylindrical can body 1,!
...N1 layer, S...frontage. Name of agent: Patent attorney Shigetaka Awano (1 person)

Claims (1)

[Claims] When forming a metal thin film by vacuum evaporation on a polyimide film running along the circumferential surface of a cylindrical can, the constituent material of the circumferential surface of the cylindrical can is Ni, and the cylindrical can and the A method for producing a metal thin film, characterized by applying a potential difference between the metal thin film and the metal thin film.