JPS6357770A - Method for coating hard carbon film on surface of metallic substrate - Google Patents

Abstract

PURPOSE:To form hard carbon films on metallic substrates as a cathode by cracking a gaseous raw material essentially consisting of a hydrocarbon by the plasma generated by a high-frequency excitation method in a metallic chamber as an anode. CONSTITUTION:The cathode 2 is insulated from the metallic chamber 1 and is inserted into the chamber 1. The many metallic substrates 3a, 3b, etc., to be treated are hung by metallic holders 4a, 4b, etc. A high-frequency source is connected to the metallic chamber 1 and the cathode 2 and after the inside of the chamber is evacuated to a reduced pressure, gaseous methane is introduced through a gas introducing port 5 into the chamber and is cracked by the plasma generated between the chamber 1 as the anode and the cathode 2 by the high-frequency excitation method, by which the hard carbon films are formed on the surfaces of the metallic substrates 3a, 3b, etc., which are to be worked.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of coating a surface of a metal substrate with a hard carbon film by high frequency plasma CVD.

[Prior art and problems]

Hydrocarbon gas is the main raw material, and the film obtained by decomposing and depositing this in discharge plasma has properties similar to diamond (
Since it was discovered that the technology has properties such as contact resistance, abrasion resistance, high hardness, lubricity, high thermal conductivity, and high insulation properties, research into the application of this technology has become active, and the manufacturing method has also been changed to the PVD method [ion Beam evaporation method (IBD method), ion blating method (IP method)], CVD method [normal pressure and low pressure CVD method, plasma CVD method (P-CVD method]), etc. have been proposed.In the PVD method, The three-dimensional coating technology on a substrate has been established to some extent, as seen in the application of TiN to watch cases, but there are many problems from the perspective of an inexpensive mass production method.

That is, the substrate must be rotated using a rotation-revolution jig, an evaporation source is required (the effective plasma space is narrow), and the number of pieces processed per batch is small. The current situation is that the device itself is expensive, so it cannot necessarily be said that it is an inexpensive processing method. On the other hand, the CVD method generally requires high processing temperatures and therefore has poor heat resistance.
Among these coating methods, the P-CVD method is preferred because it can lower the processing temperature. According to the P-CVD method in which the substrate was installed using cathode electrolyte deposition;
It is known that a highly hard carbon film can be obtained at a processing temperature of 150'C or less, and since this method does not require an evaporation source, it has the potential to become a very cheap processing method in the future. 3゜However, at present, the two-dimensional film formation and evaluation using parallel plates and types has not been considered at all, and three-dimensional coating on the substrate has not been considered at all. .

[Purpose of the invention]

The object of the present invention is to three-dimensionally coat a metal substrate with a hard carbon film with good mass productivity.

[Structure of the invention]

For this reason, the present invention uses a raw material gas containing hydrocarbon gas as its main component, and decomposes the hydrocarbon gas using plasma generated by a high-frequency excitation method. 1 death - Shiru P -CV T)
To the law:! 6, a large number of metal substrates are connected to a cathode electrode through a metal holder, and the metal chamber itself acts as an anode electrode.

In the present invention, in addition to the gold region (which is used to connect the metal holder and the metal substrate in order to maintain the substrate at cathode potential), gold (Possible to coat with carbon film).

In addition, since only the quad electrodes are arranged inside the chamber, the effective plasma space is expanded and a large number of metal substrates can be processed simultaneously.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an apparatus for coating a metal substrate with a carbon film for use as a watch band (.

Inside the metal chamber 1, only the cathode electrode 2, which is connected to the high-frequency type via a matching box, is arranged, and the metal chamber 1 itself, which has a ground potential, functions as an anode electrode. Therefore, unlike conventional P-CVD equipment, the -(J effect plasma space is expanded and a three-dimensional cathode electrode shape is possible.The metal bases of the watch band (3a, 5b, others omitted) are It is connected to and held by the cathode electrode 2 via metal holders (4a, 4h, others omitted).

After reducing the pressure in the metal chamber 1, methane gas was introduced from the gas inlet 5 to generate plasma, and then the hard carbon surface of the watch band was abraded under the following conditions.

Hard carbon film formation conditions Raw material gas: Cl-14, excitation method: high frequency (13,56M
HZ), high frequency crab 500w, gas pressure: 0
．． I Torr, Deposition rate: 021 tml+, Processing time: 10 minutes, Processing temperature: <

The hard carbon film subjected to T''J under the above conditions has an amorphous structure according to the X-ray diffraction and r(HEED) analysis results, and the FT-In spectrum shows that it contains a small amount of hydrogen in the film. It was found that the watch band itself had a complicated shape when it was bonded to a metal holder using the hole formed at the end of the watch band. Despite this, no visible color unevenness was observed depending on the location, and a three-dimensional and uniform hard carbon film coating was achieved.

From the discharge state during the treatment, it was confirmed that an ion sheath similar to that around the cathode electrode was formed around the watch band, suggesting that the watch band itself functions as a cathode electrode (i). .

Although there are still many unknowns about the formation mechanism of the hard carbon film, the P of the cathode installation we are considering
- In the CVD method, it is considered to be less than 1 g. The introduced methane gas decomposes during the discharge and becomes Cl-I 3+
The ions are accelerated by the ion sheath formed around the cathode electrode, collide with the metal substrate held at the cathode potential, and react to form a film.

At this time, the metal substrate must be at cathode potential.
The soft film with low binding energy is sputtered and released into the gas phase again, and as a result, only a hard film grows on the metal substrate. In the conventional P-CVD method, the substrate is installed as an anode in most cases, and even when installed as a cathode, the only method is to insert the substrate into the ion sheath created by the cathode electrode. As can be seen, this method is considered to be based on a completely different idea from the method of coating the metal substrate using an ion sheath that is created by the metal substrate itself by electrically connecting the metal substrate to the cathode electrode via a metal holder. Next, we investigated the metal holder that connects the metal substrate and the cathode electrode, and found that there was no significant difference in material, but under the current coating treatment conditions,
It has been found that when the distance between the metal substrate and the cathode electrode is 10 mm or less, abnormal discharge tends to occur (as a result, the hard carbon film coating becomes non-uniform).

On the other hand, when the length of the metal holder is adjusted so that the distance between the metal base and the cathode electrode is 10 mm or more,
A uniform hard carbon film coating can always be achieved, but considering the effective use of plasma space, it is better to be as short as possible without causing problems, and the distance is preferably 10 mm or more, preferably 15 mm.
It is desirable to set the shape of the metal holder so that it is about -215-2O. A similar relationship has also been confirmed regarding the spacing between metal substrates.

In this example, a watch band was used as the metal base, but it is clear that the metal base is not limited to this.In addition to ornaments such as watch cases and frames, hard carbon films can be used as three-dimensional Anything that can produce an effect by covering it is considered to be within the target range. Furthermore, in this example, the hard carbon film was coated directly onto the metal substrate, but an intermediate layer may be introduced to ensure more reliable adhesion between the metal substrate and the hard carbon film. A single layer or a laminated structure of Ti, Cr, Si, or Ge is preferable, and in consideration of three-dimensional coverage, the P-CVD method is also preferable as a method for forming the intermediate layer.

〔Effect of the invention〕

As is clear from the above explanation, by setting the metal chamber itself to an anode potential, the effective plasma space expands, making it possible to make the cathode electrode larger and more three-dimensional, and to simultaneously process a large number of metal substrates. Ta. moreover,
By electrically connecting a metal substrate to a cathode electrode via a metal holder, a hard carbon film can be coated three-dimensionally while the metal substrate remains stationary, even though the metal substrate has a complex shape. It can be said that this method is extremely mass-producible.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an apparatus for three-dimensionally coating a hard carbon film on the surface of a metal substrate in an embodiment of the present invention. 1...Metal chamber (anode electrode), 2
...Cathode electrode, 6a, 6b...Metal base, 4a, 4b...Metal holder, Fig. 1 Exhaust

Claims (2)

[Claims] (1) A large number of metal substrates held electrically connected to a metal holder are placed in a metal chamber at ground potential, and the metal substrates are placed in a gas stream containing hydrocarbon gas as the main component. A method of coating a hard carbon film on the surface of a metal substrate by applying a high frequency voltage to a large number of metal substrates via a holder and decomposing the hydrocarbon gas by plasma generated by high frequency excitation. (2) A hard carbon film is coated on the surface of the metal substrate according to claim 1, characterized in that the distance between the plurality of metal substrates and the distance between the metal substrates and the metal holder are maintained at 10 mm or more. how to.