HK1071469B - Magnetic read/write head, magnetic disk system and method for producing magnetic read/write head - Google Patents

Description

Magnetic head, magnetic disk system and method of manufacturing magnetic head

Technical Field

The present invention relates to a magnetic hard disk drive. More particularly, the present invention relates to a method of protecting a magnetic read/write head from corrosion.

Background

A hard disk drive is a common information storage device that is basically comprised of a series of rotatable disks that are accessed by magnetic reading and writing elements. These data transfer elements, commonly referred to as transducers, are typically carried by and embedded in a slider body that is held in a proximate relative position over discrete data tracks formed on the disk to perform a read or write operation. In order to maintain the transducer in proper position relative to the disk surface, an Air Bearing Surface (ABS) formed on the slider body is subjected to a fluidizing air flow that provides sufficient lift to "fly" the slider and transducer above the disk data tracks. The high speed rotation of the magnetic disk generates a stream of air flow or wind along its surface in a direction substantially parallel to the tangential velocity of the disk. The air flow cooperates with the ABS of the slider body to fly the slider above the rotating disk. In effect, the suspended slider is physically separated from the disk surface by this self-actuating air bearing.

Some of the primary objectives in ABS designs are to fly the slider and its accompanying transducer as close as possible to the surface of the rotating disk, and to maintain this constant close distance at all times regardless of changes in flying conditions. The height or separation gap between the air bearing slider and the rotating magnetic disk is typically defined as the flying height. Typically, the mounted transducer or read/write element floats only about a few nanometers above the surface of the rotating disk. The flying height of the slider is considered one of the most important parameters affecting the magnetic disk reading and writing capabilities of a mounted read/write element. The relatively small flying height allows the transducer to achieve higher resolution between different data bit locations on the disk surface, thereby increasing data density and storage capacity. With the increasing popularity of portable, small notebook computers that use relatively small, yet powerful disk drives, there is an increasing demand for ever decreasing flying heights.

As shown in FIG. 1, the ABS design of a conventional catamaran slider 5 is typically formed with a pair of parallel tracks 2 and 4 that extend along the outer edges of the slider surface facing the disk. Other ABS configurations having different surface areas and geometries, including three or more additional tracks, have also been developed. The two rails 2 and 4 typically extend from a leading edge 6 along at least a portion of the slider body length to a trailing edge 8. The leading edge 6 is defined as the edge of the slider through which the rotating disk passes towards the trailing edge 8 before traversing the entire length of the slider 5. As shown, the leading edge 6 may be tapered, although large undesirable tolerances are typically associated with this machining process. The transducer or magnetic element 7 is typically mounted at a position along the trailing edge 8 of the slider shown in FIG. 1. The rails 2 and 4 form an air bearing surface on which the slider flies and provides the necessary lift when in contact with the air flow generated by the rotating disk. As the disk rotates, the resulting wind or air flow flows under and between the catamaran slider rails 2 and 4. As the air flow passes the tracks 2 and 4 from below, the air pressure between the tracks and the disc increases, thereby providing a positive pressurization and lifting effect. Catamaran sliders generally generate sufficient lift or positive load force to enable the slider to fly at the proper height above the rotating disk. Without the rails 2 and 4, the large surface area of the slider body 5 would create an excessive air bearing surface area. Generally, as the air bearing surface area increases, the amount of lift generated also increases. Thus, without the rails, the slider flies too far from the rotating disk to achieve all of the benefits described above that can be obtained with low fly heights.

As shown in FIG. 2, the suspended head assembly 40 often provides multiple degrees of freedom to the slider, such as vertical spacing or pitch and roll angles that describe the flying height of the slider. As shown in FIG. 2, suspension 74 holds HGA40 above moving disk 76 (having edge 70 and moving in the direction indicated by arrow 80). During operation of the disk drive shown in FIG. 2, an actuator 72, such as a Voice Coil Motor (VCM), moves the HGA along an arc 75 across various diameters of the disk 76, such as the Inner Diameter (ID), Middle Diameter (MD), and Outer Diameter (OD).

Reducing the head-disk spacing requires reducing the head tip recession and the thickness of the protective layer on the slider. The protective layer, which may be in the form of a diamond-like carbon (DLC) coating, protects the magnetic material from erosion and mechanical wear (e.g., caused by contact between the slider and the recording disk). When the DLC coating becomes very thin, uniform coverage of the DLC on the magnetic material becomes a problem due to the presence of pinholes in the DLC coating, surface roughness and contaminants on the substrate. Thin DLC coatings may not be effective in avoiding corrosion and mechanical wear.

In view of the foregoing, there is a need for an improved method and system for coating a magnetic head.

Drawings

FIG. 1 is a perspective view of a slider device having a read/write head in the prior art.

FIG. 2 is a perspective view of a prior art disk drive.

FIG. 3 depicts a single layer coating applied to an underlayer of a magnetic read/write head in accordance with one embodiment of the present invention.

FIG. 4 provides a flow chart illustrating a liquid method for bonding a monolayer coating in accordance with an embodiment of the present invention.

FIG. 5 provides a schematic diagram of a system for coating a magnetic head with a monolayer of material in a liquid process, according to an embodiment of the present invention.

FIG. 6 provides a flow chart illustrating a vacuum method for bonding a monolayer coating in accordance with an embodiment of the present invention.

FIG. 7 provides a schematic diagram of a system for coating a magnetic head with a monolayer material in a vapor process, in accordance with an embodiment of the present invention.

Detailed Description

A system and method for providing erosion protection to a magnetic read/write head is disclosed. In one embodiment, a single layer of surface coating is applied to cover those portions of the magnetic read/write head under-layer that have not been covered by a previously applied diamond-like coating. This may enable thinner diamond-like coatings than the prior art. In one embodiment, the monolayer surface coating may be a self-assembled monolayer, such as for hydroxylated surfaces (e.g., SiOx, Al)₂O₃Glass, etc.) of an organosilicon compound (e.g., alkyltrichlorosilane, fluorine)Alkyltrichlorosilane, alkyltrialkoxysilane, fluoroalkyltrialkoxysilane, etc.), or carboxylic acids for aluminum or metal oxides (e.g., alkyl carboxylic acids, fluoroalkylcarboxylic acids, etc.). Alternatively, a single layer surface coating may be applied directly to the underlayer without the presence of a diamond-like coating. The monolayer surface coating may be applied by, for example, a liquid immersion method, a vapor coating method, or the like.

FIG. 3 illustrates one embodiment of a single layer coating applied to a magnetic read/write head. In one embodiment, a monolayer surface coating 310 is applied to at least partially cover the underlayer of the magnetic read/write head. In one embodiment, the bottom layer may include a magnetic layer 320 covered by a silicon or oxide layer 330. In one embodiment, a diamond-like carbon (DLC) coating 340 is applied to the underlayer, with a single layer surface coating covering those portions of the underlayer not covered by DLC. In another embodiment, the DLC has a thickness of less than 50 angstroms. The monolayer surface coating 310 bonds strongly to the silicon or oxide layer 330, but weakly to the DLC 340. Because of its weak bond to the DLC surface, the surface coating can be easily removed by a subsequent cleaning process. The cleaning process may be performed by using an organic solvent or mechanically rubbing with cloth. The surface coating remaining in the uncovered oxide areas does not add extra thickness to the magnetic spacing while still providing protection against damage.

In another embodiment where no DLC340 is applied to the silicon or oxide layer 330, a single layer surface coating 340 is applied directly to the silicon or oxide layer 330. Since the surface coating thickness can be controlled to be about 1 nanometer or less than 1 nanometer in molecular length, the actual magnetic spacing can be reduced accordingly.

In one embodiment, the type of monolayer surface coating used is strongly bonded to the oxide surface, weakly bonded to the DLC surface, has a high bulk density and high hydrophobicity. Embodiments of materials for use as a monolayer surface coating include self-assembled monolayers, such as for hydroxylated surfaces (e.g., SiOx, Al)₂O₃Glass, etc.) of an organosilicon compound (e.g., alkyltrichlorosilane, fluoroalkylTrichlorosilane, fluoroalkyltrialkoxysilane, etc.), or carboxylic acids for aluminum or metal oxides (e.g., alkyl carboxylic acids, fluoroalkylcarboxylic acids, etc.).

Example 1

In one embodiment of the present invention, a liquid method is provided for applying a monolayer surface coating to a magnetic head, as illustrated using the flow chart of FIG. 4 of the system of FIG. 5. The method begins (block 400) by dissolving a monolayer agent into a container 510 containing a solvent (block 410). In this example, the monolayer agent is Perfluorodecyltrichlorosilane (PFDTS) dissolved in 2, 2, 4-trimethylpentane solvent at a volume ratio of 1/100 to 1/200 to form monolayer solution 520 at room temperature. The magnetic read/write head 300 with the underlayer and DLC layer is suspended from a rack 530 and immersed in the monolayer solution 520 (block 420). After 10 minutes, the magnetic read/write head 300 is removed from the monolayer solution 520 by draining the monolayer solution 520 from the bottom drain 540 (block 430). Excess coating material and coating conditioner (conditioning) is removed from the head using a solvent such as 2, 2, 4-trimethylpentane (block 440), ending the process (block 450).

Example 2

In another embodiment of the present invention, a vacuum coating process is used to apply a monolayer surface coating to a magnetic head, as illustrated in the flow chart of FIG. 6 using the system of FIG. 7. The method begins (block 600) by charging a glass flask 720 with a monolayer agent 710 (block 610), and then providing a low pressure vapor 730 of an activator to a coating chamber 740. In this example, the monolayer agent 710 in the glass flask 720 is pure (96% or greater) PFDTS, which is heated to 100 ℃ by heating tape 750 to obtain a higher vapor pressure. Temperature controller 760 may control the heating of monolayer agent 710. The magnetic read/write head 300 is suspended from a rack 770 within the coating chamber (block 620). The coating chamber 740 is first cleaned by pumping it to a low vacuum level and backfilling with nitrogen gas over a number of cycles to remove residual moisture (block 630). The magnetic read/write head 300 is then exposed to the vapor 730 of the monolayer agent for 30 minutes (block 640). After the valve 780 for the activator is closed, the coating chamber 740 is cleaned again by pumping to a low vacuum and backfilling with nitrogen gas for several cycles to remove excess coating material and byproducts (block 650). The magnetic read/write head 300 is removed from the chamber 740 (block 660). The method is ended (670). The length of time may vary depending on the needs of chamber cleanliness and coating quality. In one embodiment, the temperature of the chamber is 105 degrees celsius. However, monolayer coatings have been successfully deposited on substrates over a wide temperature range of 20 ℃ to 250 ℃.

Although several embodiments have been specifically illustrated and described in detail, it will be appreciated that other modifications and variations of the present invention are covered by the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.

Claims (32)

1. A magnetic read/write head comprising:

a bottom layer; and

a single layer surface coating at least partially covering the base layer, wherein the single layer surface coating is a silicone or a carboxylic acid.

2. The magnetic read/write head of claim 1, further comprising a diamond-like carbon coating partially covering the underlayer.

3. The magnetic read/write head of claim 2, wherein the diamond-like carbon coating thickness is less than 50 angstroms.

4. The magnetic read/write head of claim 2, wherein the monolayer surface coating covers each portion of the underlayer not covered by the diamond-like carbon coating.

5. The magnetic read/write head of claim 1, wherein the monolayer surface coating is a self-assembled monolayer.

6. The magnetic read/write head of claim 5, wherein the monolayer surface coating is a fluoroalkyltrichlorosilane.

7. The magnetic read/write head of claim 5, wherein the monolayer surface coating is an alkyltrichlorosilane.

8. The magnetic read/write head of claim 5, wherein the monolayer surface coating is a fluoroalkyl trialkoxysilane.

9. The magnetic read/write head of claim 5, wherein the monolayer surface coating is an alkyltrialkoxysilane.

10. The magnetic read/write head of claim 5, wherein the monolayer surface coating is a fluorinated alkyl carboxylic acid.

11. The magnetic read/write head of claim 5, wherein the monolayer surface coating is an alkyl carboxylic acid.

12. A magnetic disk system comprising:

a disk storing data; and

a magnetic head for reading and writing data stored on a disk, the magnetic head being at least partially covered by a monolayer surface coating, wherein the monolayer surface coating is a silicone or a carboxylic acid.

13. The disk system as set forth in claim 12 wherein the diamond-like carbon coating partially covers the magnetic head.

14. The disk system as set forth in claim 13 wherein the diamond-like carbon coating is less than 50 angstroms thick.

15. The magnetic disk system of claim 13, wherein the monolayer surface coating and the diamond-like carbon coating cover disk interface locations of the magnetic head.

16. The disk system as set forth in claim 15 wherein the single layer surface coating covers each portion of the interface location not covered by the diamond-like carbon coating.

17. The disk system of claim 12 wherein the monolayer surface coating is a self-assembled monolayer.

18. The disk system as claimed in claim 17, wherein the monolayer surface coating is a fluoroalkyltrichlorosilane.

19. The disk system as claimed in claim 17, wherein the monolayer surface coating is an alkyltrichlorosilane.

20. The magnetic disk system of claim 17 wherein the monolayer surface coating is a fluoroalkyl trialkoxysilane.

21. The magnetic disk system of claim 17 wherein the monolayer surface coating is an alkyltrialkoxysilane.

22. The disk system as set forth in claim 17 wherein the monolayer surface coating is a fluorinated alkyl carboxylic acid.

23. The disk system as set forth in claim 17 wherein the monolayer surface coating is an alkyl carboxylic acid.

24. A method, comprising:

fabricating a magnetic read/write head for a disk drive; and

at least partially covering the magnetic read/write head with a monolayer surface coating by one of a liquid immersion method or a vapor coating method,

wherein the monolayer surface coating is a silicone or a carboxylic acid.

25. The method of claim 24, further comprising: the magnetic read/write head is partially covered with a diamond-like carbon coating.

26. The method of claim 25, wherein the diamond-like carbon coating thickness is less than 50 angstroms.

27. The method of claim 25, wherein the monolayer surface coating and the diamond-like carbon coating cover disk interface locations of the magnetic head.

28. The method of claim 27, wherein the monolayer surface coating covers each portion of the interface location not covered by the diamond-like carbon coating.

29. The method of claim 24, wherein the monolayer surface coating is applied via a liquid process.

30. The method of claim 29, wherein the liquid method comprises:

dissolving the monolayer agent in a solvent to produce a resultant solution;

immersing the magnetic read/write head in the solution;

removing the magnetic read/write head from the solution; and

excess coating material is removed from the magnetic read/write head.

31. The method of claim 24, wherein the monolayer surface coating is applied via a vacuum coating process.

32. The method of claim 31, wherein the vacuum coating method comprises:

loading a monolayer reagent container into a coating chamber;

placing the magnetic read/write head in the coating chamber;

purging the coating chamber with nitrogen;

pumping the coating chamber to low vacuum;

exposing the magnetic read/write head to a reagent vapor;

purging the coating chamber with nitrogen;

pumping the coating chamber to low vacuum; and

the magnetic read/write head is removed from the coating chamber.