JPS61115239A - Magnetic disk substrate - Google Patents

Abstract

PURPOSE:To decrease considerably the amplitude of the oscillation of a disk plane during high-speed rotation and to stabilize the low floating operation of a magnetic head by forming a titled substrate into a sandwich construction in which a resin material is interposed between aluminum alloy plates or glass plates. CONSTITUTION:Disks 21, 22 which are blank materials consisting of two sheets of the aluminum alloy plates or glass plates, etc. thinner than the conventional disk substrates are adhered to each other via an adhesive material 23 consisting of an epoxy resin having resistance to shrinkage to form the substrate into the sandwich construction. If the substrate is constituted in the above-mentioned manner, the damping constant of the magnetic disk substrate increases and the plane oscillation during the high-speed rotation, i.e., the amplitude at the resonance point in the oscillation of the disk plane is extremely effectively decreased to one-severals of the amplitude at the conventional resonance point shown by a solid line A as shown by a chain line B. The stabilization of the low floating operation of the magnetic head is thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a magnetic disk substrate constituting a magnetic disk medium used in a magnetic disk device.

In recent years, in magnetic disk drives, the flying height of a magnetic head has tended to become smaller and smaller as recording density has increased on magnetic disk media.

Therefore, it has become an extremely important issue to reduce surface runout and the like during high-speed rotation of the magnetic disk medium and stabilize the low flying operation of the magnetic head.

[Conventional technology]

Conventionally, generally used magnetic disk media (hard disks) usually have a substrate 1 made of aluminum alloy or the like as the main body, as shown in FIG. The recording medium layer 2 is formed by a coating method, a plating method, a sputtering method, etc., and a protective film (not shown) made of 5i02 or the like is further formed on each upper surface.
has a covered structure.

However, since the magnetic disk substrate 1 is a metal plate such as an aluminum alloy, the damping constant is small.
Mechanical resonance due to a vibration frequency of a relatively low frequency, for example, several hundred hertz (■z) is unavoidable, and the amplitude of the resonance point is large, which disturbs the stable low-flying operation of the magnetic head with respect to such magnetic disk media. In addition, there is a problem in that head crashes are likely to occur.

Furthermore, in recent years, attempts have been made to use a magnetic disk substrate made of glass or the like in place of the magnetic disk substrate 1 made of aluminum alloy or the like, but the magnetic disk substrate made of glass is susceptible to centrifugal stress during high-speed rotation. It has the disadvantage that its strength against metals is unstable compared to that of non-metallic materials, and its reliability is low.

[Problem that the invention seeks to solve]

In view of the above-mentioned conventional circumstances, the present invention increases the damping constant for a magnetic disk substrate made of metal to reduce the amplitude of mechanical resonance due to a low imaging frequency. For disk substrates, reliability is improved by strengthening the damping effect and strength against rotational centrifugal stress, and by constructing magnetic disk media using these magnetic disk substrates, This is intended to stabilize the low-flying operation of the magnetic head and extend its life.

[Means for solving problems]

In order to solve the above problems, the present invention is characterized in that the magnetic disk substrate on which the magnetic recording medium layer is formed has a sandwich structure with a resin material interposed between aluminum alloy plates or glass plates. It is.

[Effect]

That is, by forming a sandwich structure of a metal or glass magnetic disk substrate with a resin material as described above, not only the damping effect is enhanced but also the strength against rotational centrifugal stress is strengthened. It becomes possible to stabilize the low-flying operation and improve the reliability of the magnetic disk medium.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing the configuration of an embodiment of a magnetic disk substrate according to the present invention, and is made of a material circle made of two aluminum alloy plates, glass plates, etc. thinner than conventional disk substrates. The plates 21 and 22 are bonded together using a shrinkage-resistant epoxy resin adhesive 23 to form a sandwich structure. 24 is a magnetic recording medium layer made of a magnetic material and covered with a protective film (not shown).

By adopting such a substrate configuration, the damping constant of the magnetic disk substrate increases, and as is clear from the vibration frequency characteristics (compliance, vibration displacement X/force F) diagram in FIG. The amplitude of runout, that is, the vibration of the disk surface at the resonance point, is extremely effectively reduced by a few minutes, as shown by the chain line B, compared to the conventional amplitude at the resonance point, shown by the solid line A. It becomes possible to stabilize the floating operation.

In particular, in a magnetic disk substrate having a sandwich structure in which material plates 21 and 22 made of glass plates are bonded together with an epoxy resin adhesive 23, not only the damping constant increases, but also flexibility, crank prevention, etc. Mechanical strength is improved, and brittle fractures caused by centrifugal stress during high-speed rotation are effectively suppressed.

In addition, in the above embodiment, an example was explained in which two material disks were made into a Santoy-Nochi structure via an epoxy resin adhesive, but the present invention is not limited to this example. If necessary, a plurality of material disks, such as three or four, may be sandwiched together using a resin adhesive having shrinkage resistance and high attenuation for imaging, and the same effect can be obtained.

〔Effect of the invention〕

As is clear from the above description, according to the magnetic disk substrate according to the present invention, it is possible to greatly reduce the amplitude of disk surface runout during high-speed rotation, and it is possible to stabilize the low-flying operation of the magnetic head. can.

Furthermore, a magnetic disk substrate made of glass can provide a highly reliable magnetic disk substrate, especially since its mechanical strength is increased. Therefore, it is extremely useful and effective for this type of magnetic disk medium.

[Brief Description of the Drawings] Fig. 1 is a schematic sectional view showing the structure of an embodiment of the magnetic disk substrate according to the present invention, Fig. 2 is a diagram for explaining the vibration frequency characteristics of the magnetic disk substrate, and Fig. 3 is a diagram for explaining the vibration frequency characteristics of the magnetic disk substrate. 1 is a schematic cross-sectional view showing the configuration of an example of a conventional magnetic disk substrate. In the figure, reference numerals 21 and 22 indicate a material disk, and 23 indicates an epoxy resin adhesive, respectively.

Claims (1)

[Claims] 1. A magnetic disk substrate on which a magnetic recording medium layer is to be formed, characterized in that it has a sandwich structure with a resin material interposed between aluminum alloy plates or glass plates.