JPH0827928B2 - Information signal recording medium and manufacturing method thereof - Google Patents

Description

The present invention relates to an information signal recording medium such as a rigid magnetic disk, a flexible magnetic disk, an optical tracking type magnetic disk, a magneto-optical disk, and a magnetic tape, and a manufacturing method thereof. In particular, the present invention relates to an information signal recording medium in which a protective film or a magnetic layer is formed by sputtering, vapor deposition or the like, and a manufacturing method thereof.

(Prior Art) Thin-film magnetic disks and optical tracking type magnetic disks that form a magnetic layer by sputtering, vapor deposition, etc. are expected to achieve a drastic improvement in recording density in principle in comparison with coating type magnetic disks. Is being developed and put into practical use.

For example, in a Winchester type rigid magnetic disk, a NiP underlayer is generally formed on an aluminum substrate, and a magnetic recording layer and a protective film are laminated thereon.

The head of such a Winchester type rigid magnetic disk is 0.1 ~ 0.3μ from the disk in the recording and reproducing state.
Although it has been levitated by about m, it is in contact with the disc in the stopped state, so the head and the disc crash when transitioning from the suspended state to the suspended state (recording / playback state) or from the suspended state to the suspended state. There was a problem to do.
Therefore, the NiP underlayer of the disk is scratched in a circumferential shape called a texture so that the head and the disk are in stable contact with each other with a low friction coefficient.

However, since the total thickness of the magnetic film and protective film formed by sputtering is as thick as 1000 to 5000Å, it causes deterioration due to step coverage, coarsening of particles, occurrence of abnormal protrusions, etc. But,
Subtly changed by sputtering of magnetic film and protective film,
It has a drawback that it cannot maintain a proper shape. for that reason,
After the sputtering, carbon buffing and burnishing are performed to readjust the surface shape, but it is difficult to comprehensively control and manage the surface shape, and the manufacturing process becomes complicated.

Further, in the case of a perpendicular magnetic flexible disk, the output obtained from the head is small due to the characteristics of the perpendicular magnetic recording film, and therefore, in order to obtain a high output, the distance between the head and the disk should be as small as possible. Discs are always in contact.

In this case, the surface roughness of the base film or the perpendicular magnetic recording film formed by sputtering has been a serious problem for the contact between the head and the disk.

Further, in the case of a flexible disk, in both perpendicular magnetic recording and in-plane magnetic recording, there is a correlation between the magnetic characteristics and the substrate temperature during sputtering of the magnetic layer, and in order to obtain high output and high S / N, the magnetic layer The substrate temperature during sputtering
It had to be 200-300 ° C.

For this reason, it is not possible to use a cheap material having a low Tg (glass transition point) such as polyethylene terephthalate, which has been conventionally used as a substrate of the coating type flexible disk, for the substrate, and the substrate of the polyether sulfone or the polyimide cannot be used. Thus, a special and expensive magnetic material must be used, or a special and expensive magnetic material such as CoPt, which exhibits good characteristics even when sputtering is performed at a low substrate temperature, must be used for the magnetic layer.

In the case of a disk having pits or grooves on its surface, such as a capacitance tracking type magnetic disk or an optical tracking type magnetic disk as disclosed in JP-A-57-167172, a substrate having pits or grooves is compression molded or injected. Since it is formed by molding, the substrate material must have a low Tg, and the above-mentioned expensive magnetic material is used for the magnetic layer. Further, in the case of a disc having pits and grooves, there is a problem of step coverage, so the surface shape of the substrate is
It is necessary to calculate and design the surface shape after sputtering,
There was a drawback that the design became complicated.

Further, JP-B-63-19932 and JP-A-62-76023 are disclosed for the purpose of improving the crystal orientation of the perpendicularly magnetized film.

However, in Example 1 of Japanese Patent Publication No. 63-19932 and Japanese Patent Application Laid-Open No. 62-76023, the mother mold is dissolved by a chemical method, so that only the mother mold is selectively melted and magnetic properties are obtained. A special chemical that does not dissolve the layers or substrate is required, which complicates the manufacturing process. In addition, in the melting method, the remains of the matrix material were always left, and the surface roughness was also poor.

Further, in forming the magnetic layer, if the mother die heating temperature is set high in order to improve the magnetic characteristics, there is a problem that debris is more likely to remain.

The quenching and peeling method of Example 2 of Japanese Patent Publication No. 63-19932 has an effect not only on the interface between the matrix and the magnetic layer but also on other interfaces, resulting in a decrease in the peel strength of the product, resulting in reliability. Will fall.

Further, these do not have a step of forming a protective film, and it is extremely difficult to perform peeling by an external force without the protective film.
If it is done forcibly, there is a high possibility that the entire product will be damaged.

(Problems to be Solved by the Invention) In the conventional thin film magnetic disk or the disk having pits or grooves on the surface thereof, as described in the prior art due to the roughness of the disk surface or the heat resistance of the substrate. However, there are various problems such as complicated design and manufacturing process and the use of expensive materials.

Further, the Japanese Patent Publication No. 63-19932 and Japanese Patent Publication No. 62-76023 have a problem that the reliability of the product cannot be obtained.

Therefore, it is an object of the present invention to solve the above-mentioned problems by providing an information signal recording medium and a method for producing the same, in which a protective film with less friction can be formed and which does not require consideration of the heat resistance of the substrate.

(Means for Solving the Problems) As means for achieving the above object, after a protective film is laminated on a mother die, a magnetic layer is laminated on the protective film, and a substrate is provided on the magnetic layer. It is intended to provide an information signal recording medium in which a mother die and a protective film are peeled off by a physical method, and a manufacturing method thereof.

(Example) A method of manufacturing an information signal recording medium of the present invention will be described with reference to FIG.

First, on the mother die 1 shown in FIG. 1 (A), FIG.
As shown in, the protective film 2 is formed by sputtering or vapor deposition.

Next, as shown in FIG. 1 (C), a magnetic layer 3 is similarly formed on the protective film 2 by sputtering, vapor deposition or the like, and this is used as a pre-disk 4.

After that, as shown in FIG. 1 (D), the adhesive 5 is applied on the magnetic layer 3 of the pre-disk 4, and as shown in FIG. 1 (E), the substrate 6 is placed on the adhesive 5. , Glue. At this time, if the magnetic layer 3 and the substrate 6 have good adhesiveness, the adhesive 5 may not be used.

Then, after the substrate 6 is sufficiently adhered, the matrix 1 is peeled from the protective film 2 (FIG. 1 (F)) and cut into a predetermined shape, whereby the information signal recording medium 7 can be obtained. (FIG. 1 (G)).

Since the information signal recording medium 7 is formed by laminating the protective film 2, the magnetic layer 3, the adhesive layer 5, and the substrate 6 in this order as described above, the growth directions of the protective film 2 and the magnetic layer 3 are different from those of the conventional one. The structure grows in the opposite direction to the information signal recording medium, that is, from the surface (surface of the protective film 2) side of the information signal recording medium 7 toward the inside (substrate 6) side.

Since the substrate 6 is not used when forming the magnetic layer 3, it is not necessary to consider the heat resistance of the substrate 6.

Since the protective film 2 is a contact surface with the head, it is necessary to select a material having a small friction coefficient, and since the magnetic layer 3 is laminated on the protective film 2, the adhesion with the magnetic layer 3 is improved. Must be good, and since it separates from the mother die 1 in the last step, it must be a material with poor adhesion to the mother die 1.

Therefore, as a result of diligent studies, the present inventor has used carbon or PTFE as the protective film 2 and nickel or glass as the matrix 1 and set the temperature of the matrix 1 at room temperature or below room temperature to perform sputtering or Although it has been found that it is most suitable to form the protective film 2 by vapor deposition, the present invention is not limited to the materials for the matrix 1 and the protective film 2.

Further, the information signal recording medium according to the present invention may be used by coating the protective film 2 with a lubricant, if necessary.

Next, examples of the information signal recording medium and the manufacturing method thereof according to the present invention will be described.

[Example 1] A disk-shaped nickel (matrix 1) with a diameter of 130 mm, which was mirror-finished with a center line average roughness Ra of 4Å, was placed in a DC sputtering apparatus, and the vacuum was evacuated to 20 ° C. .

Then, carbon (protective film 2) was sputtered to a thickness of 300 Å with Ar gas pressure of 7 mtorr.

Next, with the vacuum exhausted state, nickel (matrix 1) is added.
After heating to 200 ° C., CoCr (magnetic layer 3) was sputtered at a Ar gas pressure of 2.5 mtorr to a thickness of 3000 Å to form a predisk 4.

Further, the pre-disk 4 was taken out from the DC sputtering device, a photocurable epoxy resin KP-500 (Asahi Denka Kogyo KK, adhesive 5) was applied, and a circular polyethylene terephthalate sheet with a diameter of 200 mm ( The substrate 6), Lumirror Q77 (manufactured by Toray Industries, Inc.), was placed on this, and uniformly pressed to make the thickness of the photocurable epoxy resin KP-500 (adhesive 5) 2 μm.

Then, this is placed under an 80 w / cm ultraviolet lamp, irradiated with ultraviolet rays for 10 seconds to completely adhere the substrate 6, and then peeled from the interface between nickel (master block 1) and carbon (protective film 2). , A disk (information signal recording medium 7) was obtained.
The peelability at this time was extremely good.

Then, the inner and outer circumferences of this disk (information signal recording medium 7) were punched out to obtain a 3.5-inch floppy disk.

Moreover, when the magnetic characteristics of this floppy disk were measured with a VSM (vibrating sample magnetometer), the vertical component Hc was 10
It was 00 Oe, and when the surface roughness was measured by a stylus type surface roughness meter, the center line average roughness Ra was 4Å, which was the same as the surface roughness of nickel (master block 1).

Then, when this floppy disk was attached to the floppy disk drive and a recording and reproducing experiment was conducted,
A value of 105 KFCI for D _{50 and} a value of 50 dB for C / N were obtained, and good recording / reproducing output was obtained.

In addition, using the same material as this Experiment 1, the conventional method,
That is, when a similar floppy disk was manufactured by a method of stacking CoCr (magnetic layer) and carbon (protective film) on a polyethylene terephthalate sheet (substrate), when the magnetic layer was sputtered, polyethylene terephthalate When the substrate is heated to a high temperature, oligomer precipitation occurs, so it can only be heated at a maximum of 100 ° C. As a result, the perpendicular coercive force Hc is 400 Oe, and the center line average roughness Ra of the surface is about 100Å, and the gap between the head and the disk is small. Since the spacing loss was large and the coercive force was small, only a value that was not practical was obtained in the recording / reproducing test.

[Example 2] A photocurable acrylic resin SD-17 (manufactured by Dainippon Ink and Chemicals, Inc.) was used as the adhesive 5, and the other was [Example 1].
A floppy disk was manufactured in the same manner as in.

Also in this case, since the matrix 1, the protective film 2, and the magnetic layer 3 are made of the same material as in [Example 1], the releasability, magnetic characteristics, reproduction output, etc. are the same as in [Example 1]. A very good value was obtained.

In addition, in both [Example 1] and [Example 2], a photo-curable resin is used as the adhesive 5. This is because the bonding step can be completed in an extremely short time. Other adhesive materials such as thermosetting resins may be used.

[Example 3] First, a pre-disk 4 was manufactured in the same manner as in [Example 1], and 15 was formed on the CoCr (magnetic layer 3) of the pre-disk 4.
A wt% solution of polyetherimide in methylene chloride was added dropwise and dried at room temperature for 6 hours.

Next, aged in a nitrogen atmosphere at 80 ° C for 24 hours,
The substrate 6 was formed.

And nickel (matrix 1) and carbon (protective film 2)
The disc was peeled off to obtain a disc (information signal recording medium 7) having a total thickness of 100 μm.

In this example, the substrate 6 and the adhesive 5 are made of the same material, but the mother die 1, the protective film 2, and the magnetic layer 3 are made of the same materials as those in [Example 1] and [Example 2]. Because
Very good values were obtained for peelability, magnetic properties, reproduction output, and the like.

[Example 4] First, in the same manner as in [Example 1], a predisk 4 was manufactured, and a polyimide precursor PIX-3400 (Hitachi Chemical Co., Ltd.) was formed on the CoCr (magnetic layer 3) of the predisk 4. Made) 5
It was spin coated at 00 rpm.

Then, they were baked in a nitrogen atmosphere in the order of 100 ° C., 200 ° C. and 350 ° C. for 1 hour each, dried and polymerized.

Then nickel (matrix 1) and carbon (protective film 2)
The disc was peeled off to obtain a disc (information signal recording medium 7) having a total thickness of 50 μm.

Also in this example, the substrate 6 and the adhesive 5 were made of the same material, and extremely good values were obtained for the peelability, the magnetic characteristics, the reproduction output, and the like.

As described above, in [Example 1] to [Example 4], nickel was used for the matrix 1 and carbon was used for the protective film 2.
Glass or PTFE may be used.

When the matrix 1 is nickel, the releasability is further improved by anodic decomposition in an alkaline solution to form NiOOH on the surface (contact surface with the protective film 2).

[Example 5] A disk-shaped quartz glass (matrix 1) having a diameter of 130 mm, which was mirror-finished with a center line average roughness Ra of 1 Å, was placed in an RF sputtering apparatus and evacuated to 20 ° C. did.

Then, the thickness of PTFE (protective film 2) is adjusted with Ar gas pressure of 8 mtorr.
Sputtering was performed up to 150 Å.

Next, the quartz glass (master block 1) is kept in the vacuum exhaust state.
Is heated to 200 ° C and subjected to ion bombardment, and then CoCr (magnetic layer 3) is formed to a thickness of 30 at Ar gas pressure of 2.5 mtorr.
Sputtering was carried out to 00Å to form pre-disk 4.

Then, a floppy disk was manufactured in the same manner as in [Example 1].

Also in this case, the releasability, the magnetic characteristics, the reproduction output, etc. were extremely good values as in [Example 1].

As described above, in [Example 1] to [Example 5], the perpendicular magnetic recording disk using the perpendicular magnetization film is used. However, when the in-plane magnetization film is used, CoNi, CoNiCr, CoPt are generally used as the magnetic material.
In this case, the Cr underlayer is replaced with the protective film 2 in this case.
The magnetic layer 3 made of these magnetic materials is formed on the above.

In this case, the disk surface (contact surface with the head)
Seen from the above, the spacing loss is equivalent to the thickness of the Cr underlayer, but since it is in-plane magnetic recording, it is not a problem as much as perpendicular magnetic recording. Conversely, surface hardness increases, corrosion resistance improves, etc. There are also advantages. Furthermore, sputtered Co-Fe ₃ O _4, by a method such as forming a Co-γ-Fe ₂ O ₃ in air annealing, to form a single layer in-plane magnetization film without Cr underlayer, a spacing loss It can be suppressed.

Then, in [Example 1] to [Example 5], all were flexible disks, but in the case of a hard disk, texture processing (protective film) was applied to the surface of the master mold 1 (contact surface with the protective film 2). 2 is formed on the surface of the protective film 2 opposite to the desired unevenness), the unevenness of an appropriate shape can be formed on the protective film 2 without the problem of step coverage.

Aluminum or glass is often used for the substrate 6 of the hard disk, but since both are materials with poor adhesiveness, in the case of aluminum, an acrylic monomer containing phosphorus (manufactured by Nippon Kayaku Co., Ltd.) The surface of the disk in contact with the magnetic layer is spin-coated with a primer whose main component is PM-1) and is subjected to a curing treatment by forming a film by irradiation of ultraviolet rays, and then a disk is manufactured. In the case of glass, the surface is spin-coated with an acrylic primer and then a curing treatment is performed by forming a film by irradiation with ultraviolet rays, or a silane coupling agent (such as A-1100 manufactured by Nippon Unicar Co., Ltd.) is used. After the surface is spin-coated, it is dried and then a disk is manufactured.

Finally, an example of a disk with tracking grooves will be shown below.

Example 6 The mother die 1 was manufactured by the same method as the stamper process of the optical disc. That is, on a photoresist master that is a glass disk coated with photoresist (photosensitive resin),
While rotating, a 1.0 μm wide tracking groove is exposed and developed with a laser light spot at a pitch of 20 μm (concentric circles). Nickel was sputtered onto this by 1000Å, followed by nickel plating, peeling and resist removal to prepare a master block 1.

Then, using this master block 1, a disk (information signal recording medium 7) was obtained in the same manner as in [Example 1].

The shape of the tracking groove at this time was the same as the shape of the tracking groove carved on the photoresist master, and the magnetic characteristics and the reproduction output were good.

(Advantages of the Invention) In the information signal recording medium and the method for manufacturing the same of the present invention, since the protective film and the magnetic layer are formed in this order on the matrix, the substrate is not required when forming the magnetic layer, and therefore the substrate The magnetic layer can be formed at an optimum temperature for the magnetic layer regardless of the heat resistance of the magnetic layer.

In addition, after forming the magnetic layer, a substrate is provided on the magnetic layer, and then the mother die is peeled off by a physical method. Furthermore, the presence of the protective film not only increases the durability of the information signal recording medium, Since the releasability from the mold is also improved, the surface of the protective film becomes extremely smooth.

Therefore, the Winchester type rigid magnetic disk or the like according to the present invention can be subjected to the texture processing without considering the step coverage, so that the readjustment of the surface shape by the carbon buff or the burnish becomes unnecessary, and the manufacturing process is simplified. .

In the case of a perpendicular magnetic flexible disk, the surface of the protective film is extremely smooth, so high output can be expected. Also, regardless of the heat resistance of the substrate, the magnetic layer can be formed at the optimum temperature for the magnetic layer,
Inexpensive and low Tg materials can be used as substrates for flexible disks, including those with in-plane magnetic recording.

Further, even in the case of a pit or grooved disc, it is not necessary to consider the step coverage, so that the design can be simplified, and the present invention has excellent effects for various information signal recording media.

[Brief description of drawings]

FIGS. 1A to 1G are views showing an information signal recording medium of the present invention and a manufacturing method thereof. 1 ... Mother mold, 2 ... Protective film, 3 ... Magnetic layer, 4 ... Pre-disk, 5 ... Adhesive, 6 ... Substrate, 7 ... Disk.

 ─────────────────────────────────────────────────── ─── Continuation of the front page Examiner Masaaki Kurano (56) References JP-A-61-214225 (JP, A) JP-B-63-19932 (JP, B2)

Claims (2)

[Claims] 1. An information signal recording medium in which a substrate, a magnetic layer and a protective film are laminated in this order, and a protective film material forming the protective film is provided from the surface side of the protective film to the magnetic layer side. An information signal recording medium, characterized in that a magnetic material that grows toward the magnetic layer and that forms the magnetic layer grows from the protective film side toward the substrate side. 2. A method of manufacturing an information signal recording medium in which a substrate, a magnetic layer and a protective film are laminated in this order, wherein the protective film is laminated on a mother die, and the magnetic film is formed on the protective film. A method for manufacturing an information signal recording medium, which comprises laminating layers, providing the substrate on the magnetic layer, and then peeling the matrix and the protective film at their interface.