JPH0344817A - Thin film type magnetic head - Google Patents

Abstract

PURPOSE:To maintain CSS durability for practical use in the area with small surface roughness where high-density recording can be performed, by providing fine projections having step slopes to make point contact to a magnetic head. CONSTITUTION:Fine projections 4 having steep slopes are provided on the surface of a substrate 1, not such projections having rather dull slopes produced by a conventional method such as texturing. ON CSS, fine projections 4 on the disk surface contact to a magnetic head on points, so that frictional resistance can be reduced and cohesion or fracture of the medium can be prevented. Thereby, good CSS characteristics can be maintained. Further a lubricant layer is provided on the disk surface and maintained among the fine projections 4 to be supplied to the top of the fine projection 4 by surface tension. Thus, good CSS life can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thin-film magnetic disk suitable for high-density recording used in magnetic storage devices of computers and the like.

Conventional technology A thin film magnetic disk using a thin metal film or a thin metal oxide film for the magnetic layer is a vacuum film formed on a substrate that has been subjected to alumite treatment, electroless N1-P plating, etc. on the surface of an aluminum alloy plate. Although a method in which a thin magnetic layer is formed using methods such as the Metsuki method has been put into practical use, the so-called contact start-stop (C3S) method is generally used, in which the magnetic head floats above the disk surface when the magnetic disk is in operation, and comes into contact with the disk surface when the magnetic disk is stopped. In this case, the surface of the disk usually has an uneven shape with grooves approximately parallel to the running direction of the magnetic head due to texturing of the substrate surface in order to withstand contact and sliding with the magnetic head when starting or stopping. A protective layer is formed on the magnetic thin film (mainly made of graphite 5i02, etc.), and a lubricant is provided on its surface. It is known that a material in which a large number of microprotrusions are formed on a plastic substrate and a magnetic thin film layer is formed thereon exhibits good practical durability (for example, JP-A-58-100221). In thin-film magnetic disks, it is possible to improve C3S durability in high recording density areas by forming a large number of fine protrusions on a substrate with good surface smoothness.However, glass substrates with good surface smoothness can be damaged during handling. Aluminum alloy plates or those with a NiP plating layer formed on their surfaces are suitable as substrates because of the danger.The surface of aluminum alloy plates has surface defects due to intermetallic compounds and segregation, and polishing It is difficult to smooth out all of these, and in N1-P plating, there are abnormal protrusions such as 1 joule, and it is difficult to smooth them sufficiently by polishing. It has become clear that almost all of the texture can be removed during texture processing.The problem that the invention aims to solve.In order to improve the recording density, it is necessary to reduce the flying distance of the magnetic head. If the surface shape is improved by reducing the height of the protrusions produced by texturing, C3S durability will be sacrificed, making it difficult to ensure practical performance. This is due to abrasion wear caused by the abrasive wear caused by the occurrence of minute scratches in the circumferential direction of the disc, and the shape of the protrusion (in the circumferential direction, it is very gentle, resembling the ridges of a mountain range). . This gentle scent changes depending on the impact force of the magnetic head.
It is easily destroyed, and when the magnetic head slides, surface contact tends to occur, and the coefficient of friction tends to be higher than in the case of point contact. The present invention was invented in view of the above-mentioned problems, and it solves the above-mentioned problems by providing a large number of steep microprotrusions on the disk surface and making point contact with the magnetic head. Means for Solving the Problems In order to achieve the above objects, the present invention (first aspect of the present invention) is to provide a thin-film magnetic disk having grooves extending substantially parallel to the circumferential direction over at least the entire recording area. A resin thin film layer is formed on the magnetic metal substrate, filling the grooves and having a large number of microprotrusions on the surface, and a magnetic thin film layer, a protective layer, and a lubricant layer are sequentially provided on the resin thin film layer. a Effect Here, in the thin film magnetic disk, the thickness of the magnetic thin film is CoP, CoNi, CoN1P, CoNiCr,
For metal-based products such as CoCr, the number is approximately 500, and for oxide-based materials such as j4e2Q3, it is approximately 1,000. Even if you add the base surface protective layer to these, the total thickness is 2,000, and the shape of the thin board surface remains almost the same. Although reflected in the disk surface shape, the greatest feature of the present invention is that the substrate is made up of micro-protrusions with a steep pattern, rather than protrusions with an averagely gentle pattern as seen in the texture processing used on conventional substrates. Therefore, C3
During S, the magnetic head makes point contact with the tips of minute protrusions on the disk surface, reducing frictional resistance, preventing adhesion and destruction, and ensuring good C8S characteristics. moreover
The lubricant layer applied to the disk surface is held between the microprotrusions and is supplied to the tips of the microprotrusions by the action of surface tension.

In addition, the resin layer on the metal substrate is embedded in the grooves on the metal substrate, so there is no peeling at the interface with the substrate, and the magnetic layer has a good C3S life. Since it is installed on top of the protrusion, the adhesive strength at this interface is also high. These factors also help improve C3S durability.

Embodiment The figure is an enlarged cross-sectional view of a part of the vicinity of the surface of a thin-film magnetic disk according to an embodiment of the present invention, cut out in the disk radial direction.

In the figure, 1 is a non-magnetic metal substrate, 11 is the main body of this metal substrate 1, and an aluminum alloy plate 12 is an N1-P electroless plating formed on this aluminum alloy plate 11 [13 is the plated layer 12]. A resin thin film layer 5 provided on the surface and extending in the circumferential direction of the substrate fills the groove 13 and has a large number of microprotrusions 4 on the surface.A magnetic thin film layer 51 provided on the resin thin film layer 3 are microscopic protrusions formed on the magnetic thin film layer 5 corresponding to the microscopic protrusions 4. 6 is a lubricant layer.

As the non-magnetic metal substrate 1, aluminum or aluminum alloy alone, titanium or titanium alloy alone, or as shown in the figure, N1-P plating 12 is applied to the surface, or α the surface is anodized, etc. Te, or 1
Macroscopically, the surface is flat, and microscopically, it is suitable to have grooves 13 extending substantially parallel to the circumferential direction over the entire recording area, but the shape of the grooves 13 is 1 or more and the depth is 50. ~1,000 people, and a pitch of 100 to 2,000 people in the disk radial direction is appropriate.
1. The grooves 13 of the substrate 1 to be formed on the substrate 1 can be manufactured by polishing to a mirror finish and then texture processing.
As a resin thin film layer 3 having a large number of microprotrusions 4 on its surface (
Although it is suitable that the top thickness is 0.05 to 5 μm and larger than the depth of the groove 13, the height of the microprotrusions 4 on the surface is 100 to 500 Å, and the height:length ratio in the surface direction is 0.1 or more. A material having an areal density of 1X10' to 1X10@ pieces/mm2 is suitable, and the method for forming this resin thin film layer 3 (for example, by making a paint containing fine particles with a particle size of 50 to 1000 and a resin binder and applying this to a substrate) is suitable. In some cases, a paint mainly composed of alpha resin is applied onto the substrate 1 to smooth the surface, and then a paint containing fine particles with a particle size of 50 to 1000 and a resin binder is applied. The fine particles used in these cases include inorganic fine particles such as alumina, silica, titanium oxide, polyamide, polyarylate, polysulquine, polyphenylene oxide,
Polyimide, epoxy, crosslinked styrene, crosslinked acrylic/k
Fine particles of polymer compounds such as cross-linked benzoguanamine and cross-linked melamine, fine carbon particles, and fine particles of metal alkoxide hydrolyzate can also be used.Also, as a binder for breeding pig resin, saturated polyesters such as polyethylene terephthalate and polybutylene terephthalate, nylon 6 ,
Polyamides such as nylon 6a, nylon 610°, nylon 11, nylon 12, polystyrene, polycarbonate, polyarylate, polysulfone, polyethersulfone, polyacrylate, polyvinyl chloride-k
Polyvinylidene chloride, polyvinyl alcohol, polyvinyl alcohol, phenoxy breeding pigs, polyimide,
Single substances, mixtures, copolymers, etc. of various resins such as polyamide-imide can be used, and crosslinkable resins such as epoxy resin, urethane resin, silicone resin, and phenolic resin can also be used. As the magnetic thin film layer 5, i&Co-Ni, Co-
Ni-Cr, Co-Cr, Co-N1-P, j
- A known thin film layer obtained by sputtering method, plating method, etc. of Fe20* etc. can be used, and if necessary, Cr, T
It is also possible to provide a base layer such as i. In the present invention, the underlayer is considered to be a part of the magnetic layer, and the appropriate thickness of the magnetic layer is 500 to 5000.As for the protective layer (Friend), the thickness of 50 to 5000 is recommended from various inorganic and organic non-magnetic materials. Human thin films can be used, especially various carbon thin films obtained by sputtering, CVD, etc. 5102 thin films obtained by wet methods are suitable as the lubricant layer 6 (perfluoroalkyl polyether and its derivative fluoroalkyl) Suitable are fatty acids, fatty acid esters, fatty acid amides, metal soaps, silicone compounds, fluorine-based surfactants, etc. into which groups have been introduced, and the appropriate amount is 0.1 to 100 mg per 1 m2 of surface. This example will be explained in more detail.A plate in which a 30 μm thick NLP film was formed by electroless plating on the surface of a mirror-puff polished A1 alloy plate with a diameter of 95 mm and a thickness of 1.2 mm. The surface was puff-polished to a mirror surface, and then textured with polishing vapor to create a substrate A having grooves extending in the circumferential direction of the substrate.Depth of grooves on substrate A +i 100 people, pitch 3.000
Because I am a human being, I created a separate A1 alloy plate that had been mirror-puff polished and directly textured with polishing paper, and used this as substrate B. 1. The depth of this groove is 450 people and the pitch is 7,000 people.
For a comparative example, the NiP film was formed and then puff-polished to a mirror finish.Substrate C was used.A polyimide solution with a concentration of 1% was applied onto each of the above substrates, and dried and baked to a thickness of 1.5 cm.
A polyvinyl alcohol aqueous solution of various concentrations (silica colloid concentration range 500-5000 ppm, silica colloid concentration range 500-5000 ppm,
Polyvinyl alcohol (concentration: 20% by weight relative to silica colloid) was applied and dried to form a resin thin film layer with microprojections on the surface.The average number of microprojections was determined from SEM photographs of the surfaces and fractured surfaces of these various substrate samples. Height, height: Find the ground density of the length in the plane direction (9) That board
Cr underlayer (thickness t, so thick) Co by sputtering method
Ni magnetic layer (600), carbon, protective layer, (250
Finally, a perfluoropolyether lubricant was applied to the surface at a concentration of 1.5+ng per 1ff12 to prepare a sample.Then, each sample was subjected to C3S measurement to evaluate C3S durability. coefficient is 1
．． When the time exceeds 0, the C8S life is determined by the number of C8S at the time of head crash.
The ss measurement was performed three times for each sample.9 The contents of each sample above and the C8S test results are summarized on the surface of the disc.

From Table 9 below, it can be seen that the C3S durability of the product of the present invention is at least a
o, ooo times or more, which is good, but in the case of the comparative example using substrate C, there was a large variation in the values in the three tests, with two out of three tests being less than 30,000 times. Mana
Force exchange not listed in this table Conventional method % Ni
A prototype in which a magnetic layer, a protective layer, and a lubricant layer according to the above embodiment were directly formed in sequence on a substrate whose surface was textured (groove depth: 100, groove pitch: 5,000). Disk C3S result (average 22.00
0 crashes and bad results Effects of the invention According to the present invention, micro protrusions are used instead of conventional texture shapes, and texture processing is used to remove abnormal protrusions and improve adhesion between the intermediate resin layer and the substrate. The present invention is capable of ensuring practical C3S durability in areas where high recording density is possible with low surface roughness.

[Brief explanation of drawings]

The figure is a partially enlarged cross-sectional view of a thin-film magnetic disk according to an embodiment of the present invention. 1...Nonmagnetic metal substrate, 3...Resin thin film seed
4...Minute protrusions 5...Magnetic thin film 6...
・Lubricant layer 13...kun

Claims (1)

[Claims] A thin resin film layer is formed on a non-magnetic metal substrate having grooves extending substantially parallel to the circumferential direction over at least the entire recording area, the resin thin film layer filling the grooves and having a large number of microprotrusions on the surface. A thin-film magnetic disk characterized in that a magnetic thin film layer, a protective layer, and a lubricant layer are sequentially provided on top of the disk.