JPH0740356B2 - Magnetic disk protective film manufacturing equipment - Google Patents

Description

The present invention relates to an apparatus for manufacturing a magnetic recording medium having a ferromagnetic metal thin film as a magnetic layer, and more particularly, an apparatus for providing a protective film on a magnetic recording layer such as a magnetic disk. It is about.

[Conventional technology]

In general, a magnetic recording medium using a ferromagnetic metal thin film as a magnetic recording layer is formed by sputtering a ferromagnetic metal material on a metal disk substrate or tape substrate, or spin-coating an emulsion in which a ferromagnetic metal material is dispersed in a resin matrix. It is manufactured by this. Although these ferromagnetic metal thin films have excellent characteristics for high-density recording, they have a drawback that they are susceptible to wear and damage due to contact with the head, and their magnetic characteristics change depending on the contact pressure of the head.

For this reason, it has been proposed to improve durability by forming a protective film of a polymer obtained by plasma polymerization of an organic compound on the surface of a ferromagnetic metal thin film. Since the silicone-based monomer is a gas or a liquid, it was not possible to easily obtain a protective film having excellent surface lubricity, surface abrasion resistance, and adhesion to a substrate.

[Problems to be solved by the invention]

As a result of earnest research conducted by the present inventors in view of the current situation,
In forming the protective film of the magnetic disk in advance, by generating plasma of the carrier gas in the presence of a sublimable solid organic compound, the organic compound is a polymer protective film having excellent performance on the surface of the magnetic disk main body. A method of precipitation was proposed.

The present invention has developed a device for specifically obtaining this protective film.

[Means for solving problems]

The apparatus of the present invention is an apparatus for depositing a protective film of a polymer obtained by plasma polymerization of an organic compound in a solid state at room temperature and atmospheric pressure on the surface of a magnetic disk body. A magnetic disk main body is provided at a deposition position, a heating body charged with the organic compound and a carrier gas outlet are sequentially disposed on the upper portion of the magnetic disk main body, and a vacuum exhaust port is attached to the bottom of a vacuum container. The compound is characterized in that the compound is heated and evaporated by a heating body to deposit a protective film on the surface of the magnetic disk body.

[Action]

In the apparatus of the present invention, a magnetic disk as a magnetic disk in the apparatus of the present invention is coated with a chemical plating layer such as Ni-P and subjected to post-treatment such as polishing, and then the surface thereof is subjected to a physical or chemical method. It forms a magnetic metal thin film.

Further, the solid organic compound in the device of the present invention is a low-melting compound having a sublimation property that is solid at room temperature and pressure.
The melting point can be known by observing a differential thermal measurement using a polarization microscope. Its value is usually 20 ℃ ~ 250 ℃ and preferably 40
It is distributed between ℃ and 150 ℃. Specific compounds include aromatic compounds such as naphthalene, anthracene, diphenylmethane, diphenylethane, dibenzyl and biphenyl, and diphenyl compounds. Also included are derivatives of sublimable compounds derived from these compounds.

As a heating body for heating these organic compounds in a vacuum vessel or vaporizing them while keeping them at room temperature, for example, a metal boat for vapor deposition is used. It is desirable to use a type in which inner lids are attached so as to be distributed in the vacuum container.

The amount of the organic compound charged in the metal boat for vapor deposition is usually 0.03 mg to 0.17 mg per cm ^{2 of the} adhered area.

Further, the carrier gas in the device of the present invention is an inert gas such as argon or nitrogen or hydrogen, and if necessary,
Hydrocarbon-based gas such as CF ₄ , CH ₄ , C ₂ H ₄ may be mixed. These gases were introduced into the vacuum vessel and 10 ^{-3 to} 1.5 Torr
Keep in the range of.

This carrier gas outlet is required to reach the surface of the magnetic disk after the gas is uniformly diffused in order to obtain a uniform protective film without directly contacting the gas with the surface of the magnetic disk. Therefore, the carrier gas outflow port and the vacuum exhaust port must be separated from each other, and a heating body for vaporizing an organic compound and a magnetic disk as well as a plasma region are sequentially disposed between them. To do. With such an arrangement, even if the sublimable substance temporarily diffuses upward, as a result of being attracted to the plasma region, a uniform polymerized film can be obtained on the surface of the magnetic disk placed on the surface of the high-voltage side electrode.

When arranging the magnetic disk in the plasma region, it is important that the monomer vapor diffusing from the monomer evaporation source is directly irradiated to the disk surface. Doing so is not preferable.

Plasma polymerized membrane and monomer evaporation source are usually 40 ^m / _m ~
It is desirable to keep the distance of 200 ^m / _m .

When plasma polymerization is performed by high frequency in the apparatus of the present invention, the energy density is set to fall within the range of 0.3 to 4 W / cm ² from the size of the high frequency output and the electrode area. Also, this power supply usually has an oscillation frequency in the short wavelength range of 13.56 MHz and is equipped with a variable capacitance type matching box.

Also, during the plasma polymerization reaction, it depends on the kind of the monomer, the gas partial pressure of the monomer, the electrode arrangement, and the temperature, which cannot be specified, but usually 5 to 10 seconds, preferably 10 to 70 seconds. The reaction conditions and the amount of monomer are selected so that a protective film having a desired film thickness can be obtained.

Thus, the thickness of the protective film obtained by the device of the present invention is usually 10
In the case of 0 Å to 1000 Å, if the film thickness is too thin, durability cannot be obtained, and if the film thickness is too thick, the spacing loss becomes large and the recording and reading characteristics are adversely affected. Depending on the situation, a strong film may not be obtained.

Further, during plasma polymerization, a temperature rise between the electrode and the magnetic disk and a sputtering phenomenon occur, but when obtaining a protective film for the magnetic disk, it is preferable that the temperature is high, and additionally, a sputtering process is performed as a pretreatment. Preliminarily and positively heating with rubbing is effective.

The device of the present invention is mainly applied to the manufacture of magnetic disks, but is also effectively applied to the manufacture of other magnetic recording materials such as magnetic tapes, floppy disks, and magnetic cards.

〔Example〕

(1) As shown in Fig. 1, inside the bell jar 3, the diameter is 130 ^m.
/ _M 2 stainless disk electrodes 2A, 2B are fixed facing each other at an interval of about 30 ^m / _m , and a ferromagnetic metal thin film is formed on the Ni-P plate substrate on the upper surface of the high voltage side electrode 2B. The magnetic disk 10 was placed, and the heating source 1 in which 20 mg of diphenyl was charged was fixed inside the small tungsten boat at a position of about 50 ^{m 2} / _m above the magnetic disk 10. Also, above the heating source 1
An inlet 8 from which argon gas was blown was fixed at a position of 50 ^m / _{m so} as to face the wall of the bell jar 3. Further, a vacuum exhaust port 5B was provided on the substrate 4 at the bottom of the bell jar 3 and connected to the vacuum pump 5A.

Then, the heating source 8 is heated to 80 ° C. by the power source 11 to evaporate the diphenyl, and argon gas is blown from the gas introduction port 8 to generate high frequency plasma (about 400 W) for 40 seconds to generate 470 Å on the magnetic disk 10 surface. A protective film was applied.

(2) Instead of the flat plate electrode in the embodiment (1), spiral type electrodes 2A 'and 2B' are used as shown in FIG. 2, and the magnetic disk 10 to be adhered is placed on the 2A 'electrode plate. A protective film formed by the device of the present invention was applied in the same manner as in Example (1).

(3) Instead of the flat plate electrode and the magnetic disk in the embodiment (1), the magnetic disk 10 is vertically arranged as shown in FIG. 3, and surrounded by the spiral type electrode 2B ', and the other embodiments In the same manner as in (1), protective films were deposited on both sides of the magnetic disk.

(4) The magnetic disk 10 is provided between the electrodes 2B ″ and 2A ″ vertically arranged as shown in FIG. 4 in place of the flat electrode in the embodiment (1), and the others are the same as those in the embodiment (1). Similarly, protective films were deposited on both sides of the magnetic disk.

〔effect〕

The apparatus of the present invention is extremely useful in forming a protective film by a plasma polymerization method on a ferromagnetic metal thin film, and is extremely useful in that a magnetic recording body having excellent durability can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of an apparatus for producing a protective film for a magnetic disk of the present invention, and FIGS. 2 to 4 are arrangement states of magnetic disks and electrodes in an apparatus for producing a protective film for a magnetic disk of the present invention. It is a schematic explanatory drawing which shows. 1 ... Heating source, 2A, 2B, 2A ', 2B', 2A ", 2B" ... Electrode, 3 ...
Vacuum container, 4 ... Bottom plate, 5A ... Vacuum pump, 5B ... Exhaust port, 8
… Gas outlet, 10… magnetic disk, 6… vacuum gauge, 9… carrier gas source.

Claims (2)

[Claims] 1. An apparatus for depositing a polymer protective film obtained by plasma polymerization of an organic compound in a solid state at room temperature and atmospheric pressure on the surface of a magnetic disk, wherein the organic compound is in a high frequency plasma region. A magnetic disk is installed at a position where the organic compound is deposited at a desired position, a heating element and a carrier gas outlet are sequentially provided on the top of the magnetic disk at desired intervals, and a vacuum exhaust port is installed at the bottom of a vacuum container. An apparatus for producing a protective film for a magnetic disk, comprising heating and evaporating a compound with a heating body to deposit a protective film on the surface of the magnetic disk. 2. An organic compound in a solid state at normal temperature and pressure is
A sublimable compound having a low melting point of 20 ° C to 250 ° C, which is composed of an aromatic compound such as naphthalene, anthracene, diphenylmethane, diphenylethane, dibenzyl and biphenyl, and a diphenyl compound. Item 1. An apparatus for producing a protective film for a magnetic disk according to item 1.