JPS62185222A - Magnetic memory body - Google Patents

Abstract

PURPOSE:To substantially assure mechanical reliability and corrosion resistance and to deal with high density recording with the thinner film by forming a thin magnetic metallic film medium on a substrate and coating the 1st-4th layers consisting of specific materials thereon. CONSTITUTION:After the metallic medium is formed on the substrate, the thin film consisting of at least one kind of the material selected from oxides and nitrides is coated thereon as the 1st layer in the presence or absence of the thin metallic film of at least one kind selected from Al, Cr, Ti, Ta and Nb. The thin metallic film of at least one kind selected from Al, Cr, Ti, Ta, and Nb is coated as the 2nd layer thereon. An imide group-contg. high polymer film is coated thereon as the 3rd layer. The material which is the salt of at lest a fatty acid and metal selected from Li, Na, K, Mg and Ca and has >=80 deg.C m.p. is coated thereon as the 4th layer. The coefft. of friction between the memory body and head is thereby considerably deceased and the mechanical reliability of the memory body is improved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magnetic recording device (magnetic disk device).

The present invention relates to a magnetic storage body (hereinafter referred to as a storage body) used in a magnetic drum device, a magnetic tape device, etc., and specifically relates to a protective film on a metal magnetic thin film medium (hereinafter referred to as a metal medium) of the storage body.

[Summary of the invention]

In the present invention, a thin film made of at least one substance selected from oxides and nitrides is coated on a metal medium as a first layer, and then a thin film made of at least one substance selected from Al, Cr, Ti, Ta, and Nb is coated on a metal medium. A thin film is coated as a second layer, then an imide group-containing polymer film is coated as a third layer, and a salt of at least a fatty acid and a metal selected from Li, Na, Mg, and Oa with a melting point of 80 ° C. By providing a storage body coated with the above-mentioned substance as the fourth layer, the coefficient of friction between the storage body and a recording/reproducing head (hereinafter referred to as a head) can be significantly reduced, and the mechanical This improves the physical reliability of the storage medium, and also dramatically improves the corrosion resistance of the storage medium against moisture and other environmental conditions.

[Prior art]

In a storage medium having a gold ki4 medium, it is essential to coat the metal medium with a protective film having sufficient mechanical reliability to withstand contact with the head and corrosion resistance to protect the metal medium from a stressful environment.

Various protective films have been proposed in the past.

Compound films typified by Sin, (including polysilicic acid), and TiN provide excellent corrosion resistance to memory bodies, but have poor lubricity and have not reached a practical level when used alone as a protective film. Furthermore, the carbonaceous film has many pinholes and has good conductivity, which adversely affects the corrosion resistance of the metal medium. Also, solid lubricant films made of BN, MC13, imide group-containing polymers, etc. had many pinholes, and therefore had insufficient anticorrosion effects. Further, in the above-mentioned film-covered storage body, repeated contact between the head and the storage body increases the static M friction coefficient between the two, resulting in a sticking phenomenon in which the spindle motor for rotating the storage body stops. Furthermore, although anti-rust agents such as dihydric phenols and lubricants such as higher alcohols, esters, and fatty acids have been proposed, there are few that are effective, and even if they are effective, they cannot maintain their effectiveness over a long period of time. I couldn't.

[Problem that the invention seeks to solve]

Conventional techniques have had problems such as physical deterioration and sticking phenomenon between the storage body and the head due to contact between the storage body and the head, and failure to ensure sufficient corrosion resistance of the metal medium of the storage body.

Therefore, the present invention is intended to solve the above problems, and its purpose is to significantly reduce the coefficient of friction between the storage body and the head, improve the mechanical reliability of the storage body, and reduce moisture content. An object of the present invention is to provide a storage medium in which the corrosion resistance of a metal medium in environments such as the above is dramatically improved.

[Means for solving problems]

In the storage body of the present invention, after forming a metal medium on a base, A
In the presence or absence of at least one metal thin film selected from L, Or, Ti, Ta, and Nb, a thin film made of at least one substance selected from oxides and nitrides is coated as the first Wl, and then At, Cr,
A thin film of at least one metal selected from T i , T a , and N b is coated as a second layer, then an imide group-containing polymer film is coated as a fifth layer, and further a thin film of at least one metal selected from T i , T a , and N b is coated as a fifth layer. .

The fourth layer is coated with a salt of a metal selected from Mg and Oa and has a melting point of 80° C. or higher.

The thin metal film between the metal medium and the oxide or nitride is coated to ensure better adhesion, and the film thickness is between 50 and 200 mm.
is sufficient and not required.

The first layer oxides are 5i02, 'I'102,
Or.

0,, Ta, o,, NbO,, A, 4tOa, etc. Nitride is Si3N4, 'I'iN, '1'a2N, AtN
, OrN, etc., and the film thickness is 200 to 800X. All of these have excellent density and insulation properties, so
It has the property of protecting the metal medium from negative environments such as moisture.

Since the metal M film of the second layer is a base metal compared to the metal medium, when the storage body is left in a stress-negative environment, it erodes before the metal medium erodes. Although the reason is unknown, it has a characteristic that even if the second layer of gold J14 thin film is etched, no products after stress are grown on the surface of the memory body. The appropriate thickness of the metal thin film is 50 to 200X.

The imide group-containing polymer film of the third layer may be made of thermosetting or thermoplastic amide-imide, imidoamine, etc., or may be mixed or laminated, and has a film thickness of 100 to 500 Å.

The above coating can be formed by any of the following coating methods: PVD methods such as vacuum evaporation, sputtering, and ion blating, CtVD.

In the metal salt of the fourth layer, the fatty acid preferably has 12 to 30 carbon atoms, and is not limited to linear, monobranched, saturated, or unsaturated, but linear ones are particularly good. Among these, metal salts having a melting point of 80° C. or higher are used, but they may be used alone or in combination.

Also, these can be dissolved in polar solvents, spin code method, spray method, etc. It may be coated by a coating method such as a pulling method or by a vacuum film forming method such as a vacuum evaporation method, and the film thickness is 50 to 2
It is 00A.

If the metal element in the metal salt is other than those mentioned above, the effect of reducing the coefficient of friction will be poor, and if the metal salt has a melting point of 80°C or lower, if the storage medium is left at high temperatures, it will gradually vaporize or impregnate the underlying layer. [Function] According to the above structure of the present invention, the metal medium is coated with a compound thin film made of at least one substance selected from oxides and nitrides having excellent anticorrosion effects. However, it is impossible to completely eliminate film defects in the thin film. When a thin film of the above-mentioned compound is coated with an imide group-containing polymer film, the film defects are considerably improved, but the results are insufficient.

Therefore, by forming a metal thin film that is more base than the metal medium between the compound thin film and the imide group-containing polymer film, the moisture resistance of the metal medium is greatly improved.

It is known that an imide group-containing polymer film has an excellent lubricating effect, but it gradually wears out due to contact with the head, and the surface of the polymer film becomes smooth. In recent years, starting failures in which the spindle motor stops due to the adhesion of molecular substances and an increase in the coefficient of static friction between the head and the storage body, leading to a staking phenomenon, have been pointed out as a major problem. Therefore, fatty acids, Di, INa, and Mg
.

The above-mentioned problem was solved by coating a salt with a metal from σa. Since these metal salts have excellent plastic deformation fluidity, they significantly reduce the coefficient of friction between the storage body and the head, and also significantly reduce the physical deterioration of the storage body and the head.

In recent years, small hard disk drives are increasingly being used in harsher environments, but since the melting point of the metal salt is 80° C. or higher, its effects can be fully demonstrated even under the above environments.

In the manner described above, it has become possible to provide a memory body with significantly improved mechanical reliability and corrosion resistance.

[Example 1] Non-magnetic alloy plating and N1-P alloy plating were coated to a thickness of about 15 μm on a custom-finished disk-shaped aluminum alloy substrate, and then polished to a thickness of 10 μm and a surface roughness of 103 μm.
107 μm or less, and further processed C0-N1-P alloy to approximately 107 μm.
The door was plated thickly.

Next, by magnetron sputtering, Sin, 3ooX,
CR with 50X1 melimidamine coating (Target: T
Ni 2200 (manufactured by Toshi) was continuously formed into a film on 1501.

Further, after immersing the above disk in the following treatment solution, 10 c
It was pulled up with tt1/jlll and coated with about 1001 sodium stearate.

Treatment liquid [Example 2] A disk having a metal medium was produced in the same manner as in Example 1. .

Next, by magnetron sputtering, T1 is 5of, Tie
, 300^, Ti 50A1 polyamideimide coating (
200 films were continuously formed using a target of 2T knee 1100 (manufactured by Toshi).

First, approximately 2sj (5/4 ice cubes) of the following treatment solution was dropped onto each side of the disk, and the disc was rotated at 500 rpm for 20 seconds to coat approximately 5° of lithium oleate.

Treatment liquid [Example 3] AooXXc was applied to a polished N1-P alloy plated disk substrate by magnetron sputtering.

-Ni-Or alloy (Co-30at, %Ni,
-7,5at,%or) 700X, TiN 40
0X and 10OA of Or, and a polyamide-imide film (Tagera) (manufactured by Tl-5o3z Toshi) was successively formed on zooX.

Next, a mixture of potassium lignocerate and magnesium behenate (gravitational ratio 1:1) was deposited at about 100X using a resistance heating vapor deposition method.
A thick film was formed.

[Example 4] A disk having a metal medium was produced in the same manner as in Example 1.

Next, by magnetron sputtering, Or, 03 was 25
A polyimide amine film (Target Tl-2130 manufactured by Toshi) was successively formed into a 150-fold film using OA and Or at 50X.

Furthermore, a film of approximately soX lithium stearate was formed using the following treatment solution and the same speed pulling method as in Example 1.

Treatment liquid [Comparative example 1] A disk was produced in accordance with Example 1 except for the film formation of Or in Example 1.

[Comparative Example 2] A disk was produced in the same manner as in Example 1 except for the coating with sodium stearate.

[Comparative Example 3] T1 in Example 2 was replaced with soX and T10. 500＾
Ti directly on the metal medium, except for the formation of Ti.

Formation of a polyamide-imide film and application of lithium oleate were performed according to Example 2.

[Comparative Example 4] T10 in Example 2. A disk was produced in accordance with Example 2 except for 1 above and the formation of the polyamide-imide film.

The quality of the discs described in the above Examples and Comparative Examples was evaluated by an aSS test and a moisture resistance test.

The aSS test determined the appearance change, static friction coefficient, and output reduction rate before and after 083.

In the moisture resistance test, the disk was left in an environment of 80° C. and 80% R, H, and the number of missing pids was confirmed as the leaving time elapsed, and the time when the number of missing pids increased was defined as the life span.

The disk of Example 1 was subjected to the same quality evaluation as described above even after being left at 100°C for 14 days.Although not mentioned in the Example, the basic material is not limited to At alloy. Plastic, glass, ceramic, etc. are optional.

〔Effect of the invention〕

As described above, according to the present invention, it has become possible to provide a disk compatible with high-density recording that has a thinner film and has sufficient mechanical reliability and corrosion resistance.

In addition, we evaluated the quality of the disk after leaving it in an environment of 100 degrees Celsius, assuming that the disk drive would be used in a harsher environment, but it was found that the characteristics did not deteriorate as a result of this, indicating that it is highly durable. Compatible discs are now available.

that's all

Claims (4)

[Claims] (1) A metal magnetic thin film medium is coated on a substrate, a thin film made of at least one substance selected from oxides and nitrides is coated on the metal magnetic thin film medium as a first layer, and then Al, A thin film of at least one metal selected from Cr, Ti, Ta, and Nb is coated as a second layer, then an imide group-containing polymer film is coated as a third layer, and at least one metal thin film selected from Cr, Ti, Ta, and Nb is coated as a third layer. 1. A magnetic memory body, characterized in that the fourth layer is coated with a substance having a melting point of 80° C. or higher, which is a salt with a metal selected from , Mg, and Ca. (2) Between the metal magnetic thin film medium and the thin film made of at least one substance selected from oxides and nitrides,
2. The magnetic memory according to claim 1, wherein a thin film of at least one metal selected from r, Ti, Ta, and Nb is formed. (3) Oxides and nitrides include Al, Cr, Ti, Ta,
2. The magnetic memory according to claim 1, which is a compound of elements selected from Nb and Si. (4) The imide group-containing polymer film is fluororesin, MOS_2
, WS_2, BN, and carbon.