JPS58116707A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To reduce aging effect of magnetic characteristic under high temperature and humidity ambient by providing a sputtering thin film of Co-P or Co-Ni-P containing phosphorus of 6-8wt% on a non-magnetic support material. CONSTITUTION:A sputtering thin film having composition of T100-yPY (T is Co or Co and Ni, y is 6wt% or more, 8wt% or less) on a non-magnetic support material. When content of P exceeds 6wt%, magnetic characteristic, particularly coercive force is lowered than that of 6wt%, but when P is 6-8wt%, magnetic characteristic is sufficient for the practical use. When content of P exceeds 6wt%, storing capability under high temperature and high humidity ambient become good and thereby film strength and bonding strength are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION IIA BEAK BACKGROUND TECHNICAL FIELD This invention relates to magnetic recording media. For more details, see Co.
-P or Co-Ni-P magnetic thin film is used as a magnetic layer to form a continuous thin film type magnetic recording medium.

Prior art and its problems In recent years, continuous thin film type magnetic recording media in which the magnetic layer is a metal magnetic thin film have been attracting attention.

One of the magnetic layer thin films of such a continuous thin film type magnetic recording medium.
As one example, Co--P or Co--Ni--P based metal thin films are known to exhibit good coercive force and squareness.

Conventionally, Co-P or Co-Ni of magnetic recording media
-P-based magnetic layer thin films are usually produced by plating methods such as electroplating and chemical plating.

However, these plating methods have various drawbacks. First, the adhesion of the thin film to the substrate and the mechanical strength of the film are low, and due to sliding with the magnetic head, the thin film may wear and peel, resulting in a decrease in output resistance. It has the disadvantage that it causes changes over time. For this reason, one layer on the thin magnetic layer is usually coated with a buffer layer, but the thickness of the buffer layer must be increased by a certain amount.

The effective clearance with the magnetic head increases, the air gap loss increases, and the recording/reproducing output decreases.

K2 also has the disadvantage that the surface properties of the thin magnetic layer are poor, resulting in a drop in output, especially in high frequencies.

Furthermore, thirdly, alkali metal ions present in the plating bath,
Acids, bases, etc. are mixed into the thin film, and these mixed impurities can cause problems such as changing and deteriorating the magnetic properties of the magnetic layer thin film and, in some cases, corroding the magnetic head.

In addition, there is a fourth drawback, although the cause is not clear.
%, when applied to audio tape, 333H!
The distortion for the tertiary &1111 injection is large, which poses a practical problem.

In response, the present inventors have previously proposed a magnetic recording medium in which a magnetic layer made of Co-P or Co-Ni-P alloy with a P content of 6 weight or less is formed by sputtering. There is (41 requests @ 55-16489
No. 9).

In this way, magnetic recording media with Co-P or Co-Ni-P magnetic layers formed by sputtering have improved magnetic properties and improved mechanical strength of the magnetic layer thin film compared to those formed by plating. The adhesive strength is extremely high, and the surface properties are also extremely good.In addition to these, the change in magnetic properties over time during long-term storage under high temperature and high humidity is also extremely small, and the third Next high school 11
The distortion for 11tILK is also extremely small.

However, even in such a medium, the deterioration of magnetic properties during long-term storage under high temperature and high humidity conditions is still large, and the film strength and adhesive strength are still insufficient.

■ Purpose of the Invention The present invention was made in view of the above circumstances, and its main purpose is to improve the Co-
It is possible to improve the P or Co-Ni-P based sputtered thin film magnetic layer to improve its storage stability, film strength, and adhesive strength.

As a result of intensive research for this purpose, the present inventors found that when the amount of P in a Co-P or Co-Ni-P sputtered thin film magnetic layer was increased from that in the previous proposal, the storage stability and The present inventors have discovered that the strength is increased and that the magnetic properties have no practical problems, leading to the present invention.

That is, the present invention is a magnetic recording medium characterized by having a sputtered thin film having a composition represented by the following formula on a nonmagnetic support.

2 T. . -7P, ゛(In the following formula, T is COl or Co and Ni
represents.

Furthermore, y is greater than 61% by weight and less than 8% by weight. Note that, as mentioned above, a Co--P or Co--Ni--P thin film with a high P content has not been known so far, regardless of whether it is produced by vapor phase deposition or by plating.

Concrete structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

In the above formula for the composition of the sputtered thin film magnetic layer in the present invention, y, that is, the P content is greater than 6% by weight,
Moreover, it is 8% by weight or less.

In this case, when the P content exceeds 6% by weight, the magnetic properties
In particular, the coercive force tends to be lower than those containing 6% by weight or less, but 11-6% by weight and 6-8% by weight of P show almost the same coercive force, and have magnetic properties that do not pose any practical problems. .

On the other hand, when it exceeds 6% by weight, the storage stability under high temperature and high humidity becomes extremely good. Furthermore, when the content exceeds 6% by weight, the film strength and adhesive strength are improved, and peeling and wear associated with long-term sliding contact of the head are also reduced.

However, when the P content exceeds 8% by weight, the coercive force decreases.

For this reason, the P content must be greater than 6% by weight and less than 8% by weight, and in this case, a medium that is collectively extremely excellent in terms of magnetic properties, storage stability, strength, etc. will be realized. .

Further, more preferable results are obtained when the P content is 6.1 to 8.0% by weight relative to qI#.

On the other hand, T may be Co alone or a combination of Co and Ni.

The Co/(Co+Ni) weight ratio (X) in TK is 0
or weighs less than 35 pounds. - If the above-mentioned X exceeds 35 weight, the magnetic properties, 411K, and coercive force will decrease.

In this case, in terms of coercive force, more preferable results can be obtained if the above-mentioned X is 0 or less than 30% KO or 28% KO.

Note that the magnetic layer thin film in this study@ has the above composition, but the thin film further contains third to fourth elements.
Even if 111 or more transition metal elements other than Go and Ni, such as Ft, Cr, kin, Mo, etc. are contained as a component in a range of less than a whisper of the total IO weight, it has such a composition. There is no particular limit to the thickness of the magnetic layer thin film, and it may vary depending on whether the magnetic recording medium is for analog recording or digital recording, or for what purpose it will be used. The thickness should be ~. However, normally 500A to several μTsuru11&
It is formed on a non-magnetic support as a continuous thin film with a thickness of .

As the support, it is sufficient to use a non-magnetic material, and there is no limit to its material and shape. Therefore, various changes can be made depending on the application of the magnetic recording medium. For supports of any material or shape,
This is because it is possible to obtain a magnetic thin film having excellent mechanical strength, adhesiveness, and good IIIi properties.

Note that it is also possible to form various underlayers on the support and form a magnetic layer on this underlayer.

In the present invention, the magnetic layer thin film is as follows.

It is deposited on the above support by sputtering.

In this case, the sputtering is performed by sputtering the target using equilibrated ions, usually at a voltage of several eV to about 100
Any known sputtering method that evaporates the target material with a kinetic energy of 8 degrees eV can be used.

Therefore, even if a plasma method is used in which the target is sputtered with ions such as Ar caused by an abnormal glow discharge in an inert gas atmosphere such as Ar, an ion beam method in which the target is irradiated with an ion beam such as Ar is not possible. May be used.

When using a plasma method, it may be so-called RF sputtering or so-called L)C sputtering, and the device configuration may be either two-pole, four-pole, etc.

Furthermore, so-called magnetron sputtering may be used. In some cases, so-called reactive sputtering, which is performed while flowing P or the like, may also be used. Furthermore, various methods can be used as the ion beam method.

In normal cases, a sintered body of Co--P or Co--Ni--P having the above composition may be used as the target.

On the other hand, as an ion source for impact ions, Ar, K
An inert gas such as r%Xe may be used. During operation, these inert gases, etc.
It is preferable to maintain a pressure Km higher than Tart. If the pressure is less than this, the magnetic properties of the obtained magnetic layer thin film, ftK coercive force, will decrease. On the other hand, if the pressure during operation is increased, , the sputtering rate will decrease.For this reason.

Pressure during operation is -ffK5X10'' ~2X10
'Torr@& is preferable.

Note that there are no particular restrictions on the grate voltage, the seven-rate current, the inter-electrode gap, etc., and these can be set to arbitrary values depending on one condition.

The magnetic layer thin film formed by this process is as follows.

It has extremely excellent magnetic properties, with a coercive force of up to 6000e and a squareness ratio of 0.7&C. Furthermore, since the magnetic thin film has no directionality, it is not limited in its use as a medium, such as in the case of oblique deposition, which makes it impossible to use it for magnetic disks.

Incidentally, since the magnetic layer thin film that is formed in this way has extremely high adhesive strength and film strength, it has the advantage that there is no need to intentionally provide a protective layer on the upper layer, but if it is necessary, It goes without saying that multiple protective layers may be used.

Such magnetic recording media are a must! It is manufactured by performing predetermined shape processing, etc. according to the requirements.

■Specific effects of the invention The magnetic recording medium of the present invention is useful as various magnetic tapes, magnetic disks, magnetic drums, magnetic sheets, magnetic cards, magnetic scales, etc. that perform analog or digital magnetic recording. be.

Even when the magnetic recording medium of the present invention is stored for a long period of time under high temperature conditions or under a chemically poor atmosphere, the magnetic properties and the like show very little change over time. In this case, the change over time is much smaller than that of a material with a P content of 6% by weight or less, which is also formed using sputtering. Also,
It is much smaller than when using the plating method, which contains a large amount of impurities, and at the same time, it is also extremely small when compared to when using the vapor deposition method.

Furthermore, the film strength and adhesive strength of the thin magnetic layer are extremely high, and peeling and abrasion due to head sliding contact are extremely low. This is also extremely low compared to the P content of 6 weight or less, and compared to other methods.

Furthermore, the magnetic properties such as coercive force Hc and squareness ratio of the magnetic layer thin film of the medium of the present invention are on the same level as when the P content is 6 weight or less, and have values that are sufficiently high for practical use.

Furthermore, the surface properties of the magnetic layer thin film are much better than those obtained by other manufacturing methods, and there is much less decrease in output, especially in one high frequency region or short wavelength recording.

In addition, distortion to the third harmonic at 333 HzK is extremely small, and K exhibits extremely excellent characteristics when used as various magnetic tapes for audio.

In this case, this distortion value is 1 when using the conventional plating method.
/311! It has also been confirmed that it is about 17,511 itL when using normal vapor deposition methods, especially oblique vapor deposition.

Specific Examples of the Invention Next, examples of the present invention will be shown and the present invention will be explained in detail.

Example 1゜(“100-X”!) At 100-yPy, the following #
A sintered body having eight compositions shown in IIK was prepared, used as a target, and a long 15jIII11 was formed by RF sputtering.
C0-N on thick polyethylene terephthalate film
A thin film of 1-P magnetic layer was deposited.

In this case, the target-film distance is 60cm,
Also, the plate voltage and plate current are each 2 K.
V, 1.50mA/- and Sita.

On the other hand, argon was used as the inert gas, and the argon pressure during operation was maintained at 0.7 x 10'' Torr.

When sputtering was performed in this manner, the deposited magnetic layer thin film was spread over the entire area of the long film.
It was confirmed that it had a uniform thickness of 00A and a uniform composition corresponding to each of the above.

For these eight types of cassette tapes, the coercive force Hc, squareness, and Itl were measured. The results are shown in Table IK below.

Separately, changes over time were measured.

That is, each tape was heated at 60°C and 95% relative humidity.
After storage for 150 days, the coercive force Hc, residual magnetic flux density Br, and MOL at <14 KHz were measured. H
Change rate (%) of C and Br and 14KHzM after storage
The output level difference between the OL and each tape before storage is shown in Table 1 below.

Furthermore, each tape was subjected to a so-called 200 pass test to evaluate peeling. That is, after marking each tape, the tape was run for 200 cycles at 40°C and 80% relative humidity.
Go twice.

After that, it was played back and the number of times the level decreased by 3 dB or more was measured.

The number of times the level drops by 3 dB or more on each tape is calculated per minute and is shown in Table IK below.

In addition, 3338 of both tapes! The distortion to the third harmonic was measured.

Separately, P and Co-Ni were used as evaporation sources at a deposition angle of 60 on a single polyethylene terephthalate film.
Oblique evaporation at 3000A thickness, x = l
5 wt%, y = 4.8 wt% Co-Ni-P
A system magnetic layer thin film was formed, a cassette tube was prepared, and the strain in this case was evaluated and found to be 5.0%.

From the results shown in Table IK, it can be seen that the composition of the present invention has significantly improved storage stability and film strength at 60°C, and has excellent magnetic properties.
It can be seen that it is equivalent to less than % by weight.

Example 2゜Example 1K works! The operating argon pressure during RF sputtering using a target with a composition of = 15wt% and F = 6.5wt is as follows! ! ! 2, a magnetic layer thin film was deposited in the same manner as in Example 1, and two types of cassette tapes were obtained.

For each tape, the coercive force Hc and squareness ratio were kept constant, and the results shown in Table 2 were obtained.

Table 2 Ar 8EHe Squareness Ratio (Torr) (Oe) 2X10” ぢ3o 0.6g7X
10” 600 063IXIO”
Too O, 5! ;l! l! From the results shown in Table 1 and Table 2, it is clear that the sputtering operating pressure had excellent properties when the sputtering operating pressure reached a predetermined value.

Agent: Patent Attorney: Yo Ishii - 13(

Claims (1)

[Scope of Claims] A magnetic recording material having a sputtered thin film having a composition represented by the following formula on an amorphous support. NiT. . -A. (In the above formula, T is COI or CO and Ni
represents. Further, y is greater than 6-fold and 8-fold or less. )