Coating processes – Direct application of electrical – magnetic – wave – or... – Polymerization of coating utilizing direct application of...
Reexamination Certificate
2001-02-16
2001-12-11
Pianalto, Bernard (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Polymerization of coating utilizing direct application of...
C427S127000, C427S299000, C427S387000, C427S490000, C427S515000, C427S527000, C427S535000, C427S558000, C427S559000, C427S578000, C427S595000
Reexamination Certificate
active
06329023
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a magnetic hard disk drive and a process for producing the same, more particularly, to a magnetic hard disk drive having loaded therein a magnetic disk and a magnetic head slider for preventing the start failure due to stiction between the magnetic head slider and the magnetic disk.
As a method for preventing the start failure of a magnetic hard disk drive due to the stiction, it is known to be effective to allow the magnetic disk-facing surface of the slider to have a low surface energy, thereby inhibiting the adhesion and buildup of a lubricant or grease onto the slider. That is to say, there is such a phenomenon that during the long term operation of the drive, the lubricant applied to the magnetic disk and the grease applied to a spindle bearing or a carriage bearing adhere to and build up on the slider and, after the stopping of the drive, they spread into the contact space between the slider and the magnetic disk to fill up the space, and consequently, a great adsorption force acts on between the slider and the magnetic disk by the meniscus force in the space, whereby the slider and the magnetic disk adhere to each other. It is the technique which intends to prevent, in this case, the buildup of the lubricant and grease on the slider by allowing the magnetic disk-facing surface of the slider to have a low surface energy, and consequently prevent the start failure.
As a prior technique for allowing the magnetic disk-facing surface of the slider to have a low surface energy, JP-A 63-64,684 discloses that a layer having a lower surface energy than that of the constituting material of the slider body, for example, a polytetrafluoroethylene (PTFE) layer is provided on the surface portion not contacting the magnetic disk on the magnetic disk-facing surface of the slider to which a magnetic head is attached.
However, according to the prior technique disclosed in JP-A 63-64,684, the magnetic disk-facing surface of the slider is composed of a PTFE layer having a low surface energy, and since the surface energy of PTFE is 15 mN/m, it has an effect of repelling the grease to prevent the grease from adhering to the slider. However, the surface is insufficient in ability to repel a lubricant for magnetic disk which lubricant has a surface energy as low as about 20 mN/m, and hence, there has been such a problem that it is difficult to prevent the lubricant from adhering to the slider and consequently prevent the start failure of the magnetic hard disk drive due to the stiction resulting from the lubricant.
From the above surface energy values of the PTFE and lubricant, it has been inferred that the contact angle of the lubricant on the magnetic disk-facing surface of the slider provided with the PTFE layer is about 40° and, at such a low contact angle, the sufficient prevention of the lubricant from adhering to the slider is difficult.
On the other hand, in JP-A 54-58,736, a method is proposed which comprises treating the surface of a slider with an alkali and thereafter adhering thereto a material having a fluorinated alkyl group and a terminal halogen, cyano or alkoxyl group to form a low surface energy layer.
When the surface to be treated is treated with an alkali, it has an effect of enhancing the adherability of the above-mentioned material having a fluorinated alkyl group and a terminal halogen, cyano or alkoxyl group, but has such a disadvantage that the magnetic layer of the magnetic head existing at the back end of the slider is eroded. Moreover, when the surface of the slider is composed of a non-metal such as a carbonaceous material or the like, there has been such a problem that the above-mentioned terminal group hardly adheres and the stability thereof becomes very low.
SUMMARY OF THE INVENTION
An object of this invention is to overcome the disadvantages of the prior art and to provide a magnetic hard disk drive in which a lubricant applied to a magnetic disk is prevented from adhering to the magnetic disk-facing surface of a slider and the start failure due to stiction resulting from adhesion of the lubricant is prevented and also a process for producing the above-mentioned magnetic hard disk drive.
This invention provides a magnetic hard disk drive comprising a magnetic disk for recording signals and a magnetic head slider facing the magnetic disk and including a magnetic head element for recording and reproducing information by scanning on the revolving magnetic disk, said slider being coated with a layer having a contact angle of 50° or more when measured by using a lubricant coated on the magnetic disk.
This invention also provides a magnetic hard disk drive comprising a magnetic disk for recording signals and a magnetic head slider facing the magnetic disk and including a magnetic head element for recording and reproducing information by scanning on the revolving magnetic disk, said slider being coated with a layer of at least one member selected from the group consisting of hydrocarbon compounds, fluorinated carbon compounds and fluorine-containing silane compounds (or fluorosilane compounds).
This invention further provides a magnetic hard disk drive comprising a magnetic disk for recording signals and a magnetic head slider facing the magnetic disk and including a magnetic head element for recording and reproducing information by scanning on the revolving magnetic disk, said slider having a protective layer and a fluorosilane compound layer thereon on the surface facing the magnetic disk, said fluorosilane compound layer being formed after activation treatment of the protective layer surface.
In this case, the same effect is obtained even when ultraviolet light irradiation is conducted before or after or both before and after the formation of the fluorosilane compound layer.
This invention still further provides a process for producing the above-mentioned magnetic hard disk drives.
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Endo Yoshishige
Horiguchi Yasuyuki
Ikeda Yukiko
Inoue Youichi
Ishii Nobuyuki
Hitachi , Ltd.
Kenyon & Kenyon
Pianalto Bernard
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