JP3125279B2 - Graphite crucible for vacuum evaporation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graphite crucible used as a container for molten metal when a metal is subjected to a vacuum deposition process.

[0002]

2. Description of the Related Art In a vacuum deposition method in which a molten metal such as aluminum or silver is evaporated under vacuum to form a metal thin film layer on the surface of a film such as plastic or paper, a graphite crucible is used for melting the metal. Have been useful.

[0003] During operation, the graphite crucible is installed under a continuously running film-like material and is kept at a high temperature by induction heating. However, vapor deposition must be performed uniformly over the entire film-like material. For this reason, conventionally, for the purpose of securing a sufficient metal evaporation surface with respect to the width of the film-like material, FIG.
As shown in the figure, a graphite crucible 2 having a round shape (typically 100 mm in inner diameter, 120 mm in outer diameter, 90 to 100 mm in height) having a cylindrical shape with a bottom at the lower part of a running film 1 is perpendicular to the running direction. And the number corresponding to the film width is arranged side by side. In this case, in order to obtain a uniform deposited film, it is necessary to control the amount of metal evaporation from each graphite crucible to be uniform, and the amount of input electricity is adjusted for each graphite crucible.

[0004]

However, in the above-mentioned processing method, about 20 round graphite crucibles are arranged and used in a wide case of a film-like material to be vapor-deposited. The operation of adjusting the quantity of electricity becomes complicated, and the inevitable spacing between graphite crucibles causes positional unevenness in the amount of metal evaporation, which hinders formation of a uniform vapor deposition layer. There are drawbacks. In addition, when the molten metal in one graphite crucible completely evaporates, the process must be completed at that point in time, so a batch operation must be completed. There is also a problem that cannot be applied to a device in which the winding device is installed outside the vacuum system).

The present invention has been developed in order to solve the above-mentioned problems of the prior art. It is possible to easily adjust the amount of electricity to be supplied, and to obtain a uniform metal film without any deposition unevenness regardless of the width of the film. It is an object of the present invention to provide a graphite crucible for vacuum vapor deposition capable of continuously forming.

[0006]

A graphite crucible for vacuum deposition according to the present invention for achieving the above object is installed below a continuously running film-like material, and the molten metal is heated by induction heating under vacuum to form the film. A crucible for vapor deposition on the object, comprising a long boat shape having a length at least equal to the width of the film object, and having an electrical resistivity of 700 to
Variation of electrical resistivity distribution is within 5% at 1000μΩcm, average pore diameter is 1μm or less, gas permeability is 0.02cm ² / sec
It has the following characteristics and is characterized by being composed of isotropic graphite which has been subjected to alumina treatment.

The most preferable long boat shape is such that the graphite crucible for vacuum evaporation is installed at right angles to the lower part of the running film-like material so that both ends of the crucible protrude to the left and right of the width of the film-like material. And the groove width in the longitudinal direction is designed to be substantially parallel in the width range of the film-like material. This form is schematically shown in FIG. 1, in which the entire width of the film-like object 1 runs on the upper surface within the length range of the long boat-shaped graphite crucible 3.

[0008] The material of the graphite crucible for vacuum evaporation of the present invention is preferably isotropic graphite.
In the range of 100 to 1000 μΩcm, the variation of the electric resistivity distribution is within 5%, the average pore diameter is 1 μm or less, and the gas permeability is 0.02.
It is desirable to use isotropic graphite of cm ² / sec or less as a base material. The characteristic that the electric resistivity is 700-1000μΩcm and the variation of the electric resistivity distribution is within 5% is necessary to provide a uniform temperature distribution to the whole crucible during induction heating. Fluctuates greatly and causes evaporation unevenness. On the other hand, if the average pore diameter exceeds 1 μm and the gas permeability exceeds 0.02 cm ² / sec, the denseness of the graphite material structure is reduced and the durability life of the crucible is shortened.

When the graphite crucible for vacuum evaporation is treated with a ceramic material such as alumina or silica, the durability life is further improved. In particular, when alumina treatment is applied to fill the pores of the graphite structure with alumina to modify the material, molten metal is prevented from entering the inside of the structure and metal carbide that weakens the material structure is effectively generated. Can be suppressed. The alumina treatment can be performed, for example, by impregnating an alumina sol into a graphite crucible and then drying.

[0010]

The graphite crucible for vacuum evaporation according to the present invention is formed in the shape of a long boat having a length at least equal to the width of the film-like material. The method of aligning and using graphite crucibles can be covered by one crucible installation. For this reason, the control of the input electric power at the time of induction heating is simplified, and extremely uniform metal evaporation without unevenness in the width direction of the film to be processed is developed.

Particularly, the crucible material is made of an electric resistivity of 700 to 1000
In the case of isotropic graphite having a variation in distribution within 5% at μΩcm, a uniform temperature distribution can be obtained as a whole crucible. Therefore, it is possible to always form a uniform metal deposition film in combination with the above-mentioned operation. When isotropic graphite having an average pore diameter of 1 μm or less and a gas permeability of 0.02 cm ² / sec or less is used as a crucible material, the durable life is improved, and further long-term stability is secured by further performing alumina treatment. In addition, if the graphite crucible for vacuum deposition of the present invention is used, the deposited metal can be replenished from the crucible end in various forms such as small lumps, flake powder, wire rod, and molten metal when the molten metal is reduced. Thus, the operation can be continuously continued without stopping the processing each time. Therefore, processing efficiency is greatly improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Example 1 Bulk specific gravity 1.90 g / cc, electric resistivity 900 μΩcm, variation in electric resistivity distribution 5%, bending strength 590 kgf / cm ² , gas permeability 0.
02cm ² / sec, coefficient of thermal expansion (RT to 1000 ° C) 5.0 × 10 ^-6 / ° C,
Processing isotropic graphite material with a porosity of 10.0 vol% and an average pore diameter of 1.0 μm, width 140mm, height 160mm, length 1900
A long boat-shaped graphite crucible for vacuum evaporation was manufactured. This crucible for vacuum evaporation was set in an induction heating coil formed so as to surround the periphery, and the temperature distribution when heated to 1500 ° C with a high-frequency current of about 1 KHz was measured. confirmed.

The above-mentioned graphite crucible for vacuum evaporation uses aluminum as an evaporation metal and a film thickness of 40 μm and a width of 740 mm on an object to be coated.
Of polyvinyl chloride, vacuum degree 5 × 10 ^-4 Torr, temperature 13
Vacuum deposition was performed at 60 ° C. until the thickness of the deposited aluminum film reached 400 Å. It was recognized that the obtained variation in the thickness of the deposited film had excellent uniformity within ± 5% of the average value.

On the other hand, the variation in the electrical resistivity distribution is
Except for 15%, the temperature distribution of the graphite crucible for vacuum evaporation made from isotropic graphite material having the same characteristics as above showed a large temperature distribution of 60 ° C, and the dispersion of the formed aluminum evaporated film showed a tendency to slightly increase. .

Example 2 The same long boat-shaped crucible for vacuum evaporation as in Example 1 was formed by using isotropic graphite having a different average pore diameter and a different gas permeability as a base material, and this was immersed in alumina sol. After being impregnated, it was dried. With respect to each of the crucibles for vacuum deposition subjected to the alumina treatment as described above, vacuum deposition of aluminum was performed under the same conditions as in Example 1, and the durability life was tested. The end point of the durable life was the time when a crack occurred on a part of the upper end surface of the crucible. Table 1 compares each endurance time with the average pore diameter and gas permeability of the crucible material.
It was shown to.

[0016]

From the results shown in Table 1, it was confirmed that the durability decreased when the average pore diameter exceeded 1 μm and the gas permeability exceeded 0.02 cm ² / sec.

[0018]

As described above, the graphite crucible for vacuum vapor deposition provided by the present invention has an integrated structure of a long boat shape different from the conventional round graphite crucible, so that the width of the film-like material to be coated can be improved. Irrespective of the above, a uniform metal deposition film can always be formed as a continuous operation. In particular, when the crucible material is a specific isotropic graphite material, and when the alumina treatment is performed, the variation of the deposited film formed is further reduced, and at the same time, the durability life can be improved. Greatly increase.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a vacuum evaporation method using a conventional round graphite crucible.

FIG. 2 is a perspective view schematically showing a vacuum deposition method when a long boat-shaped graphite crucible of the present invention is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Film-like thing 2 Graphite crucible of round shape 3 Graphite crucible of long boat shape

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Michio Usami 1-10-4-201 Tosaka Izue, Higashi-ku, Hiroshima-shi, Hiroshima (56) References JP-A-61-187126 (JP, A) JP-A-58-210164 (JP, A) JP-A-64-52674 (JP, A) JP-B-61-51336 (JP, B2) JP-B-58-48629 (JP, B2) JP-B-61-34508 (JP, B2) 58-51914 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 14/00-14/58 F27B 14/10

Claims (1)

(57) [Claims] Claims: 1. A crucible for placing a molten metal on a film by means of induction heating under vacuum, wherein the crucible is provided at a lower portion of the film running continuously and has a width at least equal to or greater than the width of the film. Equipped with a long boat shape with a length, electric resistivity of 700-1000μΩcm and electric resistivity distribution
Variation within 5%, average pore size 1μm or less
Lower, gas permeability of 0.02 cm ² / sec or less, and
Vacuum evaporation graphite crucible, wherein Rukoto such from isotropic graphite alumina processing has been performed.