JPS61151829A - Vertical magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain the titled double-face stratified vertical magnetic recording medium without any curls and whose reproducing outputs on both faces are almost equal by forming a soft magnetic film respectively on both faces of a filmy supporting body in 2 steps, and differentiating the thickness of the second-layer soft magnetic film on one surface from that on the other face. CONSTITUTION:The first-layer soft magnetic films 12 and 13, the second-layer soft magnetic films 14 and 15, and vertical magnetic films 16 and 17 are provided on both faces of a filmy supporting body 11 by vapor deposition or sputtering. In this case, curls are balanced by differentiating the thickness of the second-layer soft magnetic films 14 and 15 from each other. Since the reproducing output takes the maximal value with respect to the thickness of the soft magnetic layer, the reproducing outputs can be equalized by setting the difference in the film thickness on both sides of the maximal points. An alloy material consisting essentially of Co and Cr is preferably used as the vertical magnetic film.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a perpendicular magnetization recording medium and a method for manufacturing the same, particularly a double-sided multilayered perpendicular magnetization recording medium having a soft magnetic film and a perpendicular magnetization film, which has a smooth curl. Related to media and methods for producing the same.

[Conventional technology]

In recent years, a perpendicular magnetization recording method using a magnetic recording medium having an axis of easy magnetization in a direction perpendicular to the film surface of the recording medium has been proposed. In this perpendicular magnetization recording method, the demagnetizing field in the recording medium decreases as the recording density increases, so excellent reproduction output can be obtained and it can be said that this method is essentially suitable for high-density recording.

In order to perform magnetic recording using such perpendicular magnetization recording method, a magnetic recording medium having an axis of easy magnetization in a direction perpendicular to the film surface of the recording medium is required. Such a perpendicular magnetic recording medium is on a support made of a non-magnetic material such as a polymer material or a non-magnetic metal.

It is known that a Co--Cr alloy or the like is formed by the A-stutting method or the like.

In addition, in order to improve the recording and reproducing efficiency during perpendicular magnetization recording and reproducing, a high magnetic permeability layer made of a soft magnetic material is provided as an underlayer under the perpendicular magnetic recording layer made of the Co-Cr alloy film.
For example, a permalloy (Nl-Fe alloy) film was provided.

A so-called multilayer perpendicular magnetic recording medium is known.

Conventionally, such recording media have been produced using an apparatus as shown in FIG. 2, for example. That is, after installing the cylindrical cans 9 and 10 in the sputtering chamber 8 and evacuating the sputtering chamber, Ar gas is introduced from the gas introduction system 5, and approximately 3
While maintaining the pressure at X 10 torr, the PET film is sent out from the delivery shaft 7, and a permalloy film is formed on one side of the PET using a permalloy sputtering source 3 using a snoseter in the can 10, and then a Co- A Cr perpendicular magnetization film is formed, and then, in the can 9, a permalloy film is formed on the other side of the support from a permalloy sputter source 2, and a Co-Cr film is formed from a Co-Cr sputter source 1.
As mentioned above, the conventional method uses a cylindrical can to form a perpendicularly magnetized film and wind it up with the winding shaft 6, so the magnetic film and the film-like support are different inside each other. Therefore, the produced perpendicular magnetic recording media usually have curls, which is a practical problem.

On the other hand, perpendicular magnetization media with less curl have also been proposed (
(Special Publication No. 59-2230). That is, in a single-sided single-layer perpendicularly magnetized medium, curl non-lance is achieved by changing the thickness of the perpendicularly magnetized film on both sides of the film support.

[Problem that the invention seeks to solve]

However, such perpendicular magnetization recording media have the disadvantage that the electromagnetic characteristics change on both sides of the support, for example, the low-frequency reproduction output is greater on the thicker side of the magnetic film than on the thinner side. It has the following drawbacks. Furthermore, double-sided single-layer perpendicular magnetization recording media are compared with double-sided multilayer perpendicular magnetization recording media.

The disadvantage is that the playback output is small.

The present inventors conducted studies in order to obtain a double-sided multilayer perpendicular magnetization recording medium that has a high reproduction output, has little curl, and has approximately the same reproduction output on both sides.

The present inventors have discovered that in a double-sided multilayer perpendicular magnetization recording medium,
first#! When an attempt was made to vary the thickness of the perpendicularly magnetized film on both sides in Example No. 1, there was a condition where there was no curl, but as expected, the reproduction output was significantly different on both sides.

Furthermore, when the thickness of the soft magnetic film is varied on both sides, there are conditions under which there is no curl and the reproduction output is almost the same on both sides, but in order to obtain good curl non-lance, the difference in the thickness of both films It has been found that the recording medium has the disadvantage that the durability on both sides of the recording medium varies.

Therefore, the inventors of the present invention have conducted intensive research to solve these drawbacks and have achieved the present invention.

Accordingly, an object of the present invention is to provide a double-sided multilayer perpendicular magnetization recording medium that has almost no curl, has substantially the same reproduction output on both sides, and has almost the same durability on both sides.

[Means for solving problems]

The present inventors have achieved the above object by forming soft magnetic films on both sides of a film-like support twice by vapor deposition or splintering, and forming the second layer in a double-sided multilayer perpendicular magnetization recording medium. The soft magnetic film is made to have a different thickness on both sides of the film-like support, and the difference in film thickness is made to reduce curling, and a second layer of soft magnetic film is applied to both magnetic film surfaces. C
It has been found that this can be achieved by forming a perpendicularly magnetized film containing o-Cr as a main component.

At this time, in the present invention, the soft magnetic film of the second layer is formed by vapor deposition or snow vine while cooling the cylindrical can temperature (support temperature) to 30 ° C. It is preferable that the film is similarly formed by vapor deposition or sputtering at a temperature of the cylindrical can of 60° C. or higher, and a recording medium with good flatness can be obtained.

A feature of the present invention is that the thickness of the second layer soft magnetic film is made different on both sides of the support to maintain curl balance. ,
Which surface is made thinner is selected so that the difference in thickness will reduce curl when used as a perpendicular magnetization recording medium. In the present invention, by changing the thickness of the second layer soft magnetic film on both sides of the support, the difference in thickness is relatively small and curl can be kept small. The durability can be maintained at almost the same pressure.

The perpendicular magnetization films provided on the first-layer soft magnetic film and the second-layer soft magnetic film have the same or almost the same thickness on both surfaces.

The present invention will be explained in detail below.

FIG. 1 is a schematic enlarged cross-sectional view showing an example of a double-sided multilayer perpendicular magnetization recording medium of the present invention, in which a film-like support 110
A first layer soft magnetic film 12°13', a second layer soft magnetic film 14.15'', and a perpendicular magnetization film 1Gll?7 are provided on both sides by vapor deposition or sputtering. Only the thickness of the soft magnetic films 14 and 15 of the layers differs on both sides.

The film-like support in the present invention can be applied to polymeric materials such as polyethylene terephthalate (PET), polyimide, polyamide, polyphenylene sulfide, polyethersulfone, and polysulfone.

It has a particularly remarkable effect on materials such as PET that precipitate oridumer in the vicinity of 90 to 200 tl or emit a large amount of gas. It can also be applied to a support having a base layer.

In addition, the support is previously held in a vacuum, heat treated, or subjected to pretreatment such as glow discharge treatment,
It is desirable to reduce the emission of impurity gases from the surface and interior of the support.

As soft magnetic materials, N1-Fe N1-Fe-Mo Ni-Fe-Mo-C
u Fe Fe-Al-81Fe-Ni-OFe-Tt
N1-Fe-Cu-Cr-Mn Fe-8i-BFe
-B CFe-AI Co-V-Fe Co-Tl C
o-ZrCo-Nb-Zr Co-Ti Co-Nb-
Ta Co-N1-ZrFe N1-P Fe-P F
All general soft magnetic materials such as e-Co-Zr alloy can be used.

Since the reproduction output takes a maximum value with respect to the thickness of the soft magnetic layer, it is possible to make the reproduction output the same by setting the thickness difference on both sides of the maximum point. This maximum value generally exists between about 2000X and about 7000X, although it depends on the material composition and manufacturing method. The optimum film thickness difference for the force-reflection ratio varies depending on the type of paste (support), pretreatment conditions, vapor deposition or sputtering conditions, but is preferably 300 to 2000X.

In the present invention, it is better to balance the curl by making two soft magnetic layers and changing the thickness of the second soft magnetic layer on both sides than by changing the thickness of a single soft magnetic layer. Also, curling can be reduced with a small difference in film thickness.

The cause of this is currently unknown, but by applying K in this way, the durability of both sides remains almost unchanged.
A double-sided multilayer perpendicular magnetization recording medium with less curl can be obtained.

The perpendicularly magnetized film must have its axis of easy magnetization oriented in a direction substantially perpendicular to the surface of the support, and is made of C, which is known as a material for perpendicularly magnetized films.

An alloy material containing Cr and Cr as main components is desirable.

The film thickness is approximately 0.03 to 5 microns, and is particularly preferably approximately 0.05 to 1 micron.

As a film forming means, a so-called continuous sputtering method is preferable, in which a vapor deposition method and a sputtering method are used, and a plurality of high-speed sputtering sources are arranged around a plurality of cylindrical cans.

Various high speed sputter sources can be used as the sputter source.

In addition, the double-sided multilayered perpendicular magnetization medium of the present invention has a soft magnetic layer and a perpendicular magnetization film layer, and may also include an underlayer, an intermediate layer, an orthocoat layer, etc., as necessary. It's okay to stay.

〔Example〕

A double-sided multilayer perpendicular magnetization medium was created using the double-sided continuous sputtering apparatus shown in Figure @3.

A roll of PET film with a thickness of 50 microns is sent to the feed shaft 7.
1, and is roughly divided into three winding chambers 530 through the intermediate rows 275 to 82 and the cylindrical middle yarns 72, 73, each chamber is partitioned by a partition wall 54, 55, and each chamber is connected to an exhaust system 56, 57 and 58, respectively. It was evacuated by 59. The sputtering chamber is equipped with a DC planar magnetron type sputter cathode 91.93 having a permalloy target (Ni 78.5-Fe 21.5 weight ratio) and a Co-Cr target (C
A DC planar magnetron type sputter cathode 92.94 having an o82-Cr18 weight S) was provided.

The interior of the sputtering apparatus is 1x1o(-6
) After exhausting to a pressure below torr, the gas introduction system, 6
Gas was introduced after 0 and maintained at about 3 x 10-3 torr. On the PET film sent out from the delivery shaft 71 at a conveying speed of 40wx/-, sputtering is first applied to one side (
0 side) A permalloy film with a K of about 2500X was formed. Next, at the position of the can 73 set at the same temperature, an e-Malloy film with the same film thickness as the surface 0 is formed on the other surface (first surface) using the can 73, and then the winding shaft 74 The sample was wound to form a first layer of e-Malloy film. On top of this, the PE'f'' film, which is coated on both sides with the first permalloy film, is reversed and a permalloy film of 25001 is formed on one side using the sputter cathode 93 at the position of the can 73 set at 60°C. At the position of the can 72 set at the temperature, a Noso Malloy film of a specific thickness was formed on the zero surface by the ivy cathode 91 and wound up by the delivery shaft 71.

In this way, both sides of PIT are covered with permalloy film.
The film was conveyed in the reverse direction again, and a Co-Cr film of approximately 25,001 was formed on the zero surface by the scan/setter cathode 92 at the position of the middle yang 72 set at 120°C, and then the film was conveyed at the middle yang 72 set at 120°C. A Co-Cr film of about 2500X was formed on one side by sputtering at 730 am using the cathode 94, and the thickness of the second permalloy film provided on the zero side after being wound up by the winding shaft 74 was 1800.1900.2100.250.
It is 01.

The double-sided multilayer perpendicular magnetization film thus obtained was 5y4
' floppy disks were punched out, the curl condition and electromagnetic conversion characteristics were measured, and the results were shown to a fourth country.

Comparative example A perpendicular magnetization medium was created using the same apparatus as in the example.

Such sputtering Ivy from the equipment
After evacuation to a pressure of (-6) torr or less, gas is introduced from the gas introduction system 60 to approximately 3X10(-3)t.
It was maintained at orr. On the PET film sent out from the delivery shaft 71 at a conveying speed of 40w/-, the cathode 91 is placed at the position t of the can 72 set at +60°C.
A permalloy film having a surface K of approximately 5000 mm was formed on one side (0 side). Next, at the position of the can 73 set at the same temperature, a sputter cathode 93 is applied to the other surface (one surface) to a specific film thickness of 3900.4300.4400°46
A permalloy film of 00X was formed and wound on a winding shaft 74. Here, the temperature of the can is determined by rotating the PET film coated with permalloy film on both sides as shown in step 60 again, conveying it in the opposite direction, and sputtering the film on one side with the sputter cathode 94 at the position of the can 73 set at a constant temperature. about 2500X Co
A Co--Cr film was formed on the zero surface of the can 72, which was set at the same temperature, using a sputter cathode 92 to form a Co--Cr film of about 2500× on the zero surface, and the film was wound around the delivery shaft 71. Here, the temperature of the can was 120°C.

The double-sided multilayered perpendicularly magnetized film thus obtained was evaluated by the same method as shown in the Examples. The results are shown in Figure 4.

The TA4 diagram is a graph showing the relationship between the ratio of the total film thickness on surface 0 and the total film thickness on surface 1, and curl. The film thickness ratio of the present invention is closer to 1. Therefore, according to the present invention, the soft magnetic film on both sides of the support is made into two layers, and by changing the thickness of the second layer, the magnetic recording medium can be improved. It can be seen that when measuring a curl lance, the difference is small. Therefore, according to the present invention, the durability of the magnetic layer on both sides is almost the same even though curl-no-lance is applied as described above.

Further, according to the present invention, when the first layer of the soft magnetic layer is formed at 30°C or lower and the second layer is formed at 60°C (cylindrical can or support temperature), the difference in reproduction output fluctuation on both sides is small and A perpendicularly magnetized magnetic recording medium with good surface properties can be obtained.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a perpendicularly magnetized recording medium having good electromagnetic conversion characteristics, almost no curling, and having substantially equal durability on both sides, and also to obtain such a recording medium. This effect can be achieved by only slightly changing the thickness of the second layer of the soft magnetic layers on both sides.

[Brief explanation of drawings]

FIG. 1 is a schematic enlarged sectional view showing an example of the perpendicular magnetization recording medium of the present invention, FIG. 2 is an explanatory diagram showing an example of a conventional double-sided multilayer perpendicular magnetization recording medium manufacturing apparatus, and FIG. 3 is the invention of the present invention. FIG. 4 is a graph showing the relationship between the ratio of the thickness of the soft magnetic films on both sides of the support and the occurrence of curling. 11...Support, 12, 13...1Nth soft magnetic film, 14.15...2nd layer soft magnetic film, 16.1
7... Perpendicular magnetization film, 52... Sputtering chamber, 72.7
3... Cylindrical Can Agent Patent Attorney (8107) Kiyoshi Sasaki (and 3 others) 1st rM 2nd figure

Claims (1)

[Scope of Claims] 1) A perpendicular magnetic recording medium having a soft magnetic film and a perpendicular magnetization film formed in this order on both sides of a film-like support by vapor deposition or sputtering, wherein the soft magnetic film consists of two layers,
A perpendicular magnetization recording medium characterized in that the thickness of the soft magnetic film in contact with the perpendicular magnetization film is different on both sides of a support so as to reduce curling of the recording medium. 2) The soft magnetic film in contact with the film-like support is formed by vapor deposition or sputtering at a temperature of the support of 30° C. or lower,
The perpendicular magnetization recording medium according to claim 1, wherein the soft magnetic film in contact with the perpendicular magnetization film is formed by vapor deposition or sputtering at a support temperature of 60° C. or higher. 3) Manufacture of a perpendicular magnetization recording medium by forming a soft magnetic film and a perpendicular magnetization film mainly composed of Co-Cr on both sides of a film-like support that runs along a cylindrical can by vapor deposition or sputtering. The method is characterized in that the soft magnetic film is formed in two steps, and the thickness of the second layer of soft magnetic film is made different on both sides of the support so as to reduce curling of the recording medium. A method for manufacturing a perpendicular magnetization recording medium. 4) To form the first soft magnetic film, the temperature of the cylindrical can was set to 30℃.
The method of manufacturing a perpendicular magnetization recording medium according to claim 3, wherein the process is performed while cooling the can to a temperature of 60°C or lower, and then the second soft magnetic film is formed at a temperature of 60°C or higher in the cylindrical can.