JPH0370849B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field to Which the Invention Pertains] The present invention relates to a substrate used in a magnetic head that writes to and reads from a magnetic recording medium and has a thin film. In particular, the present invention relates to a substrate used in a thin film magnetic head suitable for performing high-density magnetic recording and a magnetic head of perpendicular magnetic recording method. [Description of Prior Art] In recent years, with the increase in the amount of information, there has been an increasing demand for higher recording densities in magnetic recording. In order to achieve this high recording density, research is being actively conducted on the improvement of various parts related to magnetic recording, such as magnetic heads, and the development of new magnetic recording methods. Regarding magnetic heads, general-purpose ring-type magnetic heads using ferrite cores are thought to have limitations in high-density magnetic recording, and as an alternative magnetic head that enables higher recording densities, JP-A No. Thin film magnetic heads have been developed, such as that disclosed in No. 55-84018. The thin film magnetic head includes a non-magnetic substrate, a write or read transducer made of a plurality of thin film layers including a write or read transducer gap layer formed on one side of the non-magnetic substrate, and and a non-magnetic protection plate covering the thin film layer. These thin film layers are typically formed by sputtering or vapor deposition on non-magnetic substrates. Furthermore, regarding magnetic recording methods, it has been shown that the conventional longitudinal magnetic recording method has a limit in increasing the recording density. A method has been proposed. When manufacturing a magnetic head for use in perpendicular magnetic recording, a soft magnetic thin film is usually formed on a nonmagnetic substrate by sputtering or vapor deposition. The substrates used in these magnetic heads require sufficient surface smoothness in order to form a thin film thereon as described above, and their surfaces are usually mirror-finished. If there are pores with a large diameter or a large number of pores in the above-mentioned substrate, even if mirror finishing is applied, the surface of the substrate will not have sufficient smoothness, and sputtering will occur on this surface. Alternatively, circular holes are present in the thin film formed by vapor deposition, and therefore, this thin film cannot have good magnetic properties. Furthermore, since gas in the pores is difficult to escape, it is difficult to obtain the degree of vacuum required during sputtering or vapor deposition. Currently, aggregates of alumina-based ceramics, which provide a smooth surface, are generally used as substrates for these magnetic heads. However, this alumina-based ceramic material has high hardness and has the disadvantage that it easily scratches the surface of the recording medium when sliding with the magnetic recording medium. To overcome this drawback, conventionally, the surface of the magnetic recording medium on which the thin-film magnetic head slides is coated with a lubricant, or the surface of the magnetic recording medium is coated with a protective film. Even if lubricant is applied, it is difficult to maintain the lubricant effect for a long time due to volatilization, etc., and the lubricant has to be reapplied periodically. This method has disadvantages in that it increases the number of coating steps and increases the distance between the thin film magnetic head and the recording medium. [Object of the Invention] The present invention makes it possible to form a thin film with extremely high surface smoothness and good magnetic properties on a mirror-finished surface, and to apply a lubricant to the surface of a magnetic recording medium. To provide a base for a magnetic head that does not cause permanent damage to the surface of a magnetic recording medium without damaging the surface of the magnetic recording medium without forming a protective film on the surface of the magnetic recording medium, and has less wear on the contact surface with the magnetic recording medium. With the goal. [Features of the Invention] The first feature of the invention is a magnetic head substrate comprising a glassy carbon material aggregate having an extremely smooth surface on which a thin film is formed and a density of 1.40 g/cm ³ or more. The second invention is characterized in that the surface on which the thin film is formed has extremely high smoothness, and the composite material contains a glassy carbon material and a thermosetting resin with a density of 1.40 g/cm ³ or more. The main feature is that it is a magnetic head base made of an aggregate of materials. In this specification, "extremely high smoothness" means that no pores with a diameter of 0.5 μm or more are formed on the surface on which the thin film is formed. Since the substrate for a magnetic head of the present invention has no holes with a diameter of 0.5 μm or more on the surface on which the thin film is formed, a thin film with good magnetic properties can be formed on the surface of the substrate. Furthermore, although the density of the substrate is not directly related to the formation of a thin film with good magnetic properties,
Even if a substrate with a low density of less than 1.40 g/cm ³ does not have pores with a diameter of 0.5 μm or more on the surface on which the thin film is formed, many pores may be formed on surfaces other than the surface on which the thin film is formed or inside the substrate. However, if this substrate is used, it is difficult to obtain the degree of vacuum required for sputtering or vapor deposition, or the loss of wear due to contact with a magnetic recording medium is large, which may impede the purpose of the present invention. cannot be achieved. Note that if the surface on which the thin film is formed does not have pores with a diameter of 0.1 μm or more, a thin film with better magnetic properties can be formed on the surface of the substrate. To further explain the present invention, the carbon material according to the present invention includes a carbon material obtained by carbonizing a thermosetting resin, a carbon material obtained by carbonizing a thermosetting resin, and a carbon material obtained by carbonizing a thermosetting resin by copolymerization, cocondensation, etc. Carbon materials obtained by curing or by significantly inhibiting crystallization through chemical treatment during the hardening or carbonization process, and carbon materials obtained by thermally decomposing low molecular weight hydrocarbons such as methane, ethylene, and benzene in the gas phase. Specifically, polyacrylonitrile-based carbon materials, rayon-based carbon materials, pitch-based carbon materials, etc.
Examples include lignin-based carbon materials, phenol-based carbon materials, furan-based carbon materials, alkyd resin-based carbon materials, unsaturated polyester-based carbon materials, and xylene resin-based carbon materials. Examples of the thermosetting resin used in the present invention include phenolic resin, epoxy resin, polyester resin, furan resin, urea resin, melamine resin, alkyd resin, and xylene resin. When these thermosetting resins are combined with the glassy carbon material, the thermosetting resin acts as a binder that binds the glassy carbon materials together,
A robust non-magnetic substrate that is strong against mechanical damage such as collision can be obtained. However, when a large amount of thermosetting resin is combined with glassy carbon material, it becomes a non-magnetic substrate that is subject to high wear.
40% by volume of glassy carbon material in composite material
The content is preferably 50% by volume or more. The magnetic head substrate of the present invention is composed of an aggregate of the above-mentioned carbon material or a composite of a carbon material and a thermosetting resin. Various well-known molding methods such as casting, compression, and extrusion are used to manufacture these aggregates, but with a diameter of 0.5μ
In order to obtain an aggregate with a density of 1.40 g/cm ³ or more and no pores larger than m or more, when using the casting method, for example, a carbon material precursor (thermosetting resin with a curing agent or heat) can be obtained. In the step of obtaining a cured product, the curing agent is uniformly dispersed or heated uniformly, and the curing speed is adjusted so as not to become too fast. In the case of compression or extrusion molding, it can be obtained, for example, by wetting a carbon material with a thermosetting resin and molding it with as few voids as possible. [Effects of the Invention] As described above, the magnetic head substrate of the present invention has the surface smoothness required for forming a thin film on the substrate, and sufficient smoothness can be obtained by mirror finishing. Furthermore, a thin film with good magnetic properties can be formed on a substrate by sputtering or vapor deposition. Furthermore, the lubricity between the magnetic recording medium and the magnetic recording medium can be maintained for a long time without using a lubricant, and the surface of the magnetic recording medium is not damaged and the amount of loss due to wear is small. Furthermore, due to the conductivity of the carbon material, static electricity is not generated, and there is an effect that dust does not adhere to the substrate and the magnetic recording medium. When the above-mentioned carbon material aggregate or composite material aggregate according to the present invention is used in a part other than the base that comes into contact with a magnetic recording medium, for example, a protective plate of a thin film magnetic head, a support of a soft magnetic thin film of a perpendicular magnetic recording head, etc. This can be said to be preferable because it provides sustainable lubricity between the magnetic recording media. [Explanation based on Examples] Hereinafter, the present invention will be explained in more detail using Examples in order to show specific embodiments of the magnetic head substrate of the present invention. It does not limit the technical scope of the invention. Example A furan-based glassy carbon material aggregate manufactured by cast molding and having characteristics of density 1.49 g/cm ³ , Shore hardness 112, and thermal conductivity 3 kcal/mhr°C was cut into the shape and dimensions shown in the figure, The sliding surface A with the recording medium and the surface B on which the thin film is formed were roughly polished and then gradually finely polished, and finally mirror-finished with #15000 emery paper to prepare a model substrate 1. When mirror-finished surface B was observed using a scanning electron microscope, it was found that this surface had a diameter of 0.5 μm.
No pores larger than this were observed, and only pores with a diameter of 0.01 μm or less were observed. In order to evaluate the friction between this model substrate 1 and the magnetic recording medium, the A side of the substrate 1 and the Co-adhered γ
-Fe ₂ O ₃ coating film, Ni-P plating thin film and Co-
The dynamic friction characteristics with respect to the Cr sputtering thin film were measured using a friction tester, and the condition of the surface A of the substrate 1 and the surface of the magnetic recording medium was observed with the naked eye. The results are shown in Table 1. The friction testing device used in the measurements is a device that can measure dynamic friction characteristics under conditions close to actual usage conditions, as described in Japanese Patent Laid-Open No. 55-128142. Next, this model substrate 1 was cut along the broken line C-C' in the figure, and a 1 μm thick layer was placed on the B side of one of the cut pieces.
A Co-Zr-Nb alloy thin film was formed by sputtering to a thickness of 0.3 μm on the B side of the other cut piece.
A Co-Zr-Nb alloy thin film was also formed by sputtering. After heat-treating these thin films in a rotating magnetic field, the coercive force Hc of each thin film was measured using a vibrating magnetometer for soft magnetic thin films.
The results are shown in Table 2. Example A furan-based glassy carbon material aggregate manufactured by cast molding and having a density of 1.47 g/cm ³ , a Shore hardness of 100, and a thermal conductivity of 7 kcal/mhr°C was treated in the same manner as in Example 1. When a model substrate 1 as shown in the figure was prepared and surface B was observed using a scanning electron microscope, no pores with a diameter of 0.5 μm or more were found on this surface, but pores with a diameter of 0.05 μm or less were observed on this surface. All I could do was get caught. Thereafter, the friction between the model substrate 1 and the magnetic recording medium and the coercive force of the thin film were measured in the same manner as in the examples.
Note that the thin film was made by the same method as in the example. These results are shown in Tables 1 and 2. Example Density 1.45 g/cm ³ manufactured by cast molding,
A phenolic glassy carbon material aggregate having properties of Shore hardness of 78 and thermal conductivity of 15 kcal/mhr°C was treated in the same manner as in Example 1 to prepare a model substrate 1 as shown in the figure, and surface B was scanned. When observed using an electron microscope, no pores with a diameter of 0.5 μm or more were observed on this surface, and only pores with a diameter of about 0.2 μm were observed. Thereafter, the friction between the model substrate 1 and the magnetic recording medium and the coercive force of the thin film were measured in the same manner as in the examples.
Note that the thin film was made by the same method as in the example. These results are shown in Tables 1 and 2. Example Consisting of 70% by volume of phenolic glassy carbon fiber (manufactured by Nippon Kynor Co., Ltd., registered trademark name: Kynol) and 30% by volume of general-purpose resol resin for lamination,
A composite glass-like carbon material aggregate having a density of 1.46 g/cm ³ molded by compression molding was processed in the same manner as in the example to prepare a model substrate 1 as shown in the figure, and surface B was examined using a scanning electron microscope. When I observed it,
No pores with a diameter of 0.5 μm or more were found on this surface.
Only pores with a diameter of 0.4 μm or less were observed. Thereafter, the friction between the model substrate 1 and the magnetic recording medium and the coercive force of the thin film were measured in the same manner as in the examples.
Note that the thin film was made by the same method as in the example. These results are shown in Tables 1 and 2. Comparative Example A furan-based glassy carbon material aggregate manufactured by casting and having a density of 1.37 g/cm ³ , a Shore hardness of 80, and a thermal conductivity of 10 kcal/mhr°C was treated in the same manner as in the example. When a model substrate 1 as shown in the figure was prepared and surface B was observed with a metallurgical microscope, pores with a diameter of less than 0.5 μm were observed on this surface, but there were also pores with a diameter of 0.6 to 0.7 μm. It was seen. The coercive forces of the model substrate 1 and the thin film of the magnetic recording medium were then measured in the same manner as in the examples. Note that the thin film was made by the same method as in the example. The results are shown in Table 2. Comparative Example A phenolic glassy carbon material aggregate manufactured by casting and having a density of 1.35 g/cm ³ , a Shore hardness of 70, and a thermal conductivity of 13 kcal/mhr°C was treated in the same manner as in Example 1. When a model substrate 1 as shown in the figure was prepared and surface B was observed with a metallurgical microscope, pores with a diameter of less than 0.5 μm were observed on this surface, but there were also pores with a diameter of 0.9 to 1.1 μm. was also seen. Thereafter, the coercive force of the model substrate 1 and the thin film of the magnetic recording medium was measured in the same manner as in the example. Note that the thin film was made by the same method as in the example. The results are shown in Table 2. Comparative example Alumina ceramics (manufactured by Nippon Electric Glass Co., Ltd.)
A model substrate 1 as shown in the figure was prepared by treating Neoceram (trade name) in the same manner as in the example, and when surface B was observed with a scanning electron microscope, it was found that there were also pores with a diameter of 0.5 μm or more on this surface. not seen, diameter
Only pores of 0.01 μm or less were observed. Hereinafter, the friction between the model substrate 1 and the magnetic recording medium was measured in the same manner as in the example. The results are shown in Table 1. (Test Results) As is clear from Tables 1 and 2, the magnetic head substrate of the present invention has excellent lubricity with the magnetic recording medium, does not damage the head sliding surface and the recording medium, and It can be seen that the coercive force is small and the magnetic properties are excellent.

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[Table] Means exceeding the above.

[Brief explanation of drawings]

The figure is an external perspective view of a model board made of a material used in a magnetic head according to an embodiment of the present invention. 1...Model board.

Claims (1)

[Claims] 1. In a magnetic head substrate in which a thin film constituting a write/read converter for writing to or reading from a magnetic recording medium is formed on one surface, the surface on which the thin film is formed is extremely A substrate for a magnetic head, characterized in that it is composed of a glassy carbon material aggregate having high smoothness and a density of 1.40 g/cm ³ or more. 2. In a magnetic head substrate in which a thin film constituting a write/read converter for writing to or reading from a magnetic recording medium is formed on one surface, the surface on which the thin film is formed has extremely high smoothness. A substrate for a magnetic head, comprising a composite material aggregate containing a glassy carbon material having a density of 1.40 g/cm ³ or more and a thermosetting resin.