Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
2000-08-18
2004-03-16
Lund, Jeffrie R. (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C118S7230AN, C118S719000, C118S715000, C156S345430, C156S345440, C156S345310
Reexamination Certificate
active
06705245
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for forming polymer continuously by DC plasma polymerization, and more particularly, to an apparatus used for the treatment of the surface of metal for thereby maximizing the utilization of a substrate by modifying the surface of the substrate or forming a new film material.
2. Description of the Background Art
Generally, when the surface of a substrate such as a metal plate is treated by plasma discharge, a coating layer having excellent hardness, abrasion resistance, etc. is formed. A product having the coating layer is used as a magnetic disk, optical disk, carbide tool, and the like. In addition, when a paint-coated film formed on the surface of a steel plate is plasma polymerized, the steel plate becomes hardened and has excellent durability and corrosion resistance.
Meanwhile, when it is made possible to continuously form polymer by plasma polymerization, the productivity of the polymerized product is improved. With regard to insulating materials including resin, fabric cloth, nonwaven fabric, etc. of a band-type substrate, it is relatively easy to continuously form polymer by plasma polymerization, and a number of apparatuses has already been proposed. (Japanese Patent 58-120859, 61-21105, and 2-103206).
However, in the case that the band-type metal used as the substrate is plasma polymerized by high frequency discharge while keeping it at an ungrounded potential, there is a problem in forming polymer continuously. The reason thereof is that since metal materials have conductivity, a discharge voltage is applied not only to an electrode, but also to the metallic substrate and metallic parts contacting the substrate. Thus, in the case that a metallic substrate is plasma polymerized by high frequency discharge while keeping it at an ungrounded potential, abnormal discharge occurs due to the conductivity of the metal and thus the apparatus is contaminated. In addition, the coated layer on the polymerized surface of the metallic substrate is apt to be powderized, or peeled off due to unstable discharge, resulting in degeneration of the coated layer and degradation of the product.
On the other hand, it is also possible to continuously form polymer by plasma polymerization while keeping a grounded potential. That is, the band-type metal material is plasma polymerized while keeping it at the grounded potential and continuously transporting the same. However, in the case that the grounded potential is kept, it is difficult to acquire deposition characteristics such as abrasion resistance which can be acquired in case of the ungrounded potential with respect to the plasma-polymerized substrate
In Japanese Laid-open Patent Hei 6-136506, an apparatus for forming polymer by plasma polymerization is disclosed. In the apparatus, a band-type substrate can be plasma polymerized by suppressing abnormal discharge and unstable discharge while keeping the above-mentioned ungrounded potential is disclosed. This apparatus makes it possible to generate plasma discharge under a predetermined pressure atmosphere and thus apply a discharge voltage only to electrode.
The apparatus comprises: a transport chamber
10
wherein a set of a unwinding roll
11
and a winding roll
12
, a pair of tension rolls
13
and
14
, and a support opening
15
are allocated; a deposition chamber
20
wherein deposition is performed on a substrate; a roll-shaped electrode
21
and an opposed electrode
22
allocated opposite to the roll-shaped electrode; an insulating shielding plate
30
prepared between the transport chamber and the deposition chamber; two differential openings
31
and
32
formed on the shielding plate for maintaining the pressure difference between the transport chamber and the deposition chamber; vacuum pumps
17
and
18
for controlling the pressure atmosphere of the transport chamber and deposition chamber; a gas injection opening
23
for injecting raw material gas into the deposition chamber; and exhaust openings
16
and
24
connected to the transport chamber and deposition chamber.
A substrate
1
to be plasma polymerized is transported from the unwinding roll
11
in the transport chamber
10
, and is introduced into the deposition chamber
20
via the differential opening
31
at one side. Then, it is transported to the roll-shaped electrode
21
, is passed through the vicinity of the opposed electrode
22
, and thereafter is transported to the winding roll
12
in the transport chamber
10
via the differential opening
32
at the other side. In the above-described apparatus, in a process where the band-type substrate transported from the transport chamber to the deposition chamber is plasma polymerized by high frequency discharge and is send back to the transport chamber, the atmosphere of the deposition chamber is a glow discharge atmosphere, and the atmosphere of the transport chamber is a non-glow discharge atmosphere, which is lower than that of the deposition chamber.
Plasma discharge has a tendency to be generated under a predetermined pressure atmosphere according to the type of the discharge. For example, plasma polymerization is apt to be generated under a pressure atmosphere of 10
3
~10 torr in general. Beyond this range, it is difficult to generate a glow discharge. Thus, even in the case that a band-type conductive metal material is polymerized, it is preferred that the transport chamber area and the deposition chamber are divided from each other, each of the areas is, maintained at a different pressure atmosphere by the differential opening, the deposition chamber is under the pressure atmosphere of 10
3
~10 torr, and the transport chamber is under a pressure atmosphere beyond the above range, whereby, a glow discharge is generated in the deposition chamber while it is difficult to generate a glow discharge in the transport chamber, thus suppressing abnormal discharge.
Therefore, it is said that discharge is achieved not in the entire substrate, but in the deposition chamber alone by differentiating the pressure atmosphere of the chambers from each other as described above, whereby unpredictable discharge of metal materials excepting electrode portions is prevented with respect to the band-type metal substrate maintained at the ungrounded potential, thus forming a coating layer of a good film material.
However, in the apparatus, in a roll-shaped electrode as a discharge electrode and a curved opposite electrode as an opposite electrode are installed in the deposition chamber wherein plasma reaction occurs by high frequency discharge, and one surface of the substrate to be deposited is contacted by the roll electrode. In this case, of both surfaces of the substrate between the roll electrode and the opposite electrode wherein plasma reaction is actively occurred, deposition occurs only on the surface opposed to the opposite electrode, so there is an inconvenience of performing plasma treatment once more in order to deposit the other surface.
In addition, in the apparatus for forming polymer by plasma polymerization according to the conventional art, since discharge is achieved using high frequency power, (+), (−) power sources are alternatively applied to the substrate used as an electrode. At this time, in the case that the substrate is under the glow discharge atmosphere in case of (−), discharge tends to occur in the entire parts of the substrate irrespective of the position of the opposite electrode. The reason thereof is that discharge begins at the time when electrons are emitted from portions of a low potential.
In addition, in the apparatus for forming polymer by plasma polymerization according to the conventional art, in order that discharge is occurred only at a portion at which the opposite electrode is positioned, a differential opening is formed between the transport chamber and the deposition chamber, and the atmosphere of the transport chamber and the deposition chamber, are differentiated from each other, that is, the transport chamber
Jeong Young-Man
Lee Su-Won
Youn Dong-Sik
Lund Jeffrie R.
Ostrolenk Faber Gerb & Soffen, LLP
Zervigon Rudy
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