JP2000057562A - Low static friction laser bump structure for magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce static friction for a head, a coefft. of static friction (COS), a take-off speed, and contact area of a head on a CSS region by controlling height of bump, diameter of a periphery part, and an interval between adjacent bump. SOLUTION: This is a method for forming a bump 20 having a crater shape of low static friction on a magnetic recording medium 10. The bump 20 is formed on a CSS region 12 of a medium which is made by a laser pulse, stopped at the inside of a head converting data, and floats from there. Each bump has lower hollow than a nominal surface 13 of a medium, and a ring periphery part 201 surrounding hollow 200 having appropriate bump height.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a structure of a crater type bump provided on a magnetic recording medium.

[0002]

2. Description of the Related Art Bumps are produced by a laser and are formed on a CSS area (contact-start-stop area) of a medium which stops in a data conversion head. The structure of the laser bump is designed to reduce static friction with the head and increase the durability of the media. Hard magnetic recording media (typically hard discs)
(Textured) on the CSS area of
The method of forming e) is known in the prior art.

[0003] MZT (mec)
mechanical zone texture) and LZT
(Laser zone texture). The purpose of these tissues is to reduce the static friction of the media against the head. The invention particularly relates to LZT.

The LZT method used on magnetic recording media is disclosed in US Pat. Nos. 5,062,021 and 5,510,872 by Magnetic Peripherals.
81, and International Busin
U.S. Patent No. 553 by ess Machines
No. 28922 and No. 5631408. All of these use laser pulses to form crater-shaped bumps on the recording medium. However, they do not provide any answer about reducing the static friction of the tissue area against the transducing head.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a magnetic recording medium that reduces the static friction of the head, the COS, the take-off speed, and the contact area of the head over the CSS area, thereby improving the durability of the head and the medium. It is intended to provide a low static friction laser bump structure for use.

[0006]

Means for Solving the Problems The present invention for solving the above problems is constituted as follows. The first aspect of the present invention provides a contact-start-stop area [co
ntact-start-stop (CSS) area], a low static friction laser bump structure for a magnetic recording medium having a plurality of crater-shaped laser bumps formed thereon, wherein each of the laser bumps is lower than a nominal surface of the medium. A depression, an annular edge surrounding the depression, and a bump height (Hb) in the range of 13 to 30 μm on the nominal surface, and any two adjacent bumps are average in both radial and circumferential directions. It is characterized by being arranged at intervals of 25 μm.

According to a second aspect of the present invention, the height of the bump is in the range of 10 to 27 nm after the magnetic recording medium has passed through the manufacturing steps of sputtering and lubrication.

The invention according to claim 3 is characterized in that the bump height is 18 nm.

According to a fourth aspect of the present invention, the height of the bump is 20 nm.

The invention according to claim 5 is characterized in that any two adjacent bumps are arranged with an average interval of 30 μm or more.

The invention according to claim 6 is characterized in that any two adjacent bumps are arranged with an interval of 35 μm or more on average.

The invention according to claim 7 is that the annular edge portion is
It has a diameter of 4.5 to 7 μm.

[0013] In the invention according to claim 8, the annular edge portion is
It has a diameter of 6.3 μm.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The main objects of the present invention are lower static friction, lower coefficient of friction, lower take-off speed, and smaller contact area of the head with the media, and consequently the magnetic field. An object of the present invention is to provide an LZT structure that extends the life of a recording medium.

The present invention discloses a method for forming a plurality of crater-shaped bumps on a magnetic recording medium.
The bump is created by a laser pulse and stops in the data transducing head and lifts the medium out of it.
It is formed on an SS (contact-start-stop) region. The structure of the laser bump is designed to reduce static friction with the head and to increase the durability of the media.

According to the present invention, each crater-type bump formed by the laser pulse and formed in the CSS region of the magnetic recording medium includes a center-centered depression lower than the nominal surface of the magnetic recording medium and the depression. And a raised edge surrounding it. This edge has a height above the nominal surface.

The above objects of the present invention can be achieved by controlling the edge height (also referred to as bump height), the edge diameter, and the spacing between adjacent bumps.

The objects and features of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings.

Prior to disclosing the present invention, terms relating to the present invention will be reviewed again.

As shown in FIG. 1, the magnetic recording medium 10
It is a part of a hard disk drive not shown. The medium 10 includes a data area 11 for storing data and a contact-start-stop area 12 (contact-start-s) generally located around the center of the medium.
topzone 12).

Contact-start-stop region 12
(Abbreviated as CSS area) is for stopping in a conversion head (not shown) of the disk drive. The head contacts the surface of the CSS area 12 when the medium 10 and the head stop. The medium 10 starts rotating before the data area is read or written.
After reaching the predetermined speed, the head “takes off” and moves toward the data area 11 due to the airflow generated by the bumps in the CSS area. After the data read / write operation is completed, the head moves to the CSS area 1
Return to 2 and stop.

The coefficient of friction (COS) is calculated by the following equation: COS = f / F. Where f is the maximum frictional force of the surface of the CSS area against the head, and F is the normal force of the head pressed against the surface of the CSS area.

The frictional force f varies with the material of the transducing head, and the normal force F varies with the head support mechanism. By ignoring the lubrication state, the influence of the structure of the laser bump on the friction state can be objectively evaluated by the COS value.

The take-off speed is determined by the head in the CSS area 1
2 shows the rotation speed of the medium when it starts to leave. In general, an earlier take-off is due to the CSS area 12 of the head.
Friction time against the surface of the head and the frictional wear of the head and media. Therefore, it is virtually desirable to have a lower take-off speed.

The contact area indicates the surface on which the data conversion head stops and contacts the CSS area 12. For the same situation of the friction surface, a larger contact area will result in greater frictional wear. Therefore, it is desirable to minimize the contact area as much as possible in order to reduce the consumption of the data conversion head.

The control of the laser bumps, ie the height of the edges, the diameter of the edges and the spacing between adjacent bumps,
The present invention reduces the static friction on the head, COS, take-off speed and the contact area of the head on the CSS area,
Therefore, the durability of the head and the medium is improved.

Referring to a partially enlarged plan view of the CSS region 12 in FIG. 2, a plurality of laser bumps 20
It is formed on the CSS region 12 of the medium with p (radial bump spacing) and Csp (circumferential bump spacing). Rsp represents an interval between adjacent bumps in the radial direction of the medium. Csp represents the circumferential distance between adjacent bump media. Referring to the cross-sectional view of the bump in FIG. 3, the bump 20 has a crater-like shape having a depression 200 and a circular edge 201. Hb (bump height) indicates the height of the edge 201 rising from the nominal surface 13 of the CSS region. Db indicates the diameter of the edge 201 obtained at the top. According to the invention, Db is between 4.5 μm and 7 μm
Is preferably 6.3 μm.

FIGS. 4 and 5 are charts of experiments showing the relationship between Hb and COS, and the relationship between Hb and the take-off speed of the head. As shown in FIG. 4, Hb is 15 nm (nan
Oter), the COS approaches a constant (1 or less). Still referring to FIG. 5, during the initial CSS cycle of the magnetic recording medium 10 (the cycle in which the head takes off from the CSS area and returns to the CSS area and stops), the takeoff speed recorded by a circle is proportional to Hb. looks like. This means that higher bumps result in higher take-off speeds and do not provide an optimized height.

Therefore, 10000 of the CCS cycle
After repeated tests, the statistical result of the pick-off rate indicated by the diamond is a curve with a lower base where the relationship between the pick-off rate and Hb is lower, and where Hb is approximately 13 to 30 nm. , The take-off speed is 120 ips (inch per second) or less. Also, by referring to FIG. 4, we have confirmed that Hb is preferably in the range of 13 to 30 nm. Because the substrate of the medium 10 is
It is cleaned and sputtered during the manufacturing process to reduce the height of edge 201 relative to nominal surface 13. The height of the bumps of the completed medium is about 10 to 27 nm. In a preferred embodiment, Hb is about 18 nm or 20 nm.
nm is preferred.

FIGS. 6 and 7 show the distance between bumps (Rs
6 is a chart of an experiment showing a relationship between the COS of the head (including p and Csp) and the head COS, and a relationship between a bump interval and a head take-off speed.

FIG. 6 shows the COS as a function of bump spacing under three environmental conditions: 80% RH (relative humidity) at 35 ° C., 8% RH at 60 ° C., and 45% RH at 25 ° C. . They have a COS of 25 and an Rsp and Csp of 25.
It shows that when it exceeds μm, it stabilizes to a lower constant value. Further, referring to FIG. 7, the initial CS
At any time in the S cycle (indicated by a circle) or the repeated 10,000 cycle test (indicated by a diamond), the take-off rate is an approximately constant value. Because of this we
I learned that bump spacing does not affect COS.

According to FIGS. 6 and 7, the average of the bump intervals is preferably 25 μm or more. In one preferred embodiment, approximately 30 or 35 μm Hb is used.

FIG. 8 is a chart of an experiment showing the relationship between the bump interval and the contact area of the head. From the drawings, we can note that by making the laser bump spacing greater than 25 μm, the contact area of the head over the CSS area is less than 1500 μm, which is ideal as a reduced contact area.

As described above, by controlling the structure of the laser bump, ie, Hb, the diameter of the edge, and the spacing between adjacent bumps, the present invention provides a method for reducing head static friction,
COS, take-off speed, and the contact area of the head over the CSS area could be reduced, resulting in improved head and media durability.

It will be apparent to those skilled in the art that various modifications can be made without departing from the scope of the present invention.

[0036]

The present invention provides a low static friction laser for magnetic recording media which reduces head static friction, COS, take-off speed, and head contact area over the CSS area, thereby improving head and media durability. A bump structure can be provided.

[Brief description of the drawings]

FIG. 1 CSS of a disk-shaped magnetic recording medium
It is a top view which shows a (contact-start-stop) area | region.

FIG. 2 is a partially enlarged view of a CSS region showing an arrangement of laser bumps.

FIG. 3 is a longitudinal sectional view showing a shape of a laser bump.

FIG. 4 is a chart of an experiment showing a relationship between a bump height and a coefficient of static friction on a head.

FIG. 5 is a chart of an experiment showing a relationship between a bump height and a head take-off speed.

FIG. 6 is a table of an experiment showing a relationship between a bump interval and a coefficient of static friction with respect to a head.

FIG. 7 is a chart of an experiment showing a relationship between a bump interval and a head take-off speed.

FIG. 8 is a table of an experiment showing a relationship between a bump interval and a contact area of a head with a medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Magnetic recording medium 11 ... Data area 12 ... Contact-start-stop (CSS) area 13 ... Nominal surface 20 ... Laser bump 200 ... Depression 201 ... Annular edge

Claims (8)

[Claims] 1. A low static friction laser bump structure for a magnetic recording medium having a plurality of crater-shaped laser bumps formed on a contact-start-stop area [contact-start-stop (CSS) area]. The laser bump has a depression lower than the nominal surface of the medium, an annular edge surrounding the depression, and a bump height (Hb) in the range of 13 to 30 μm on the nominal surface. A low static friction laser bump structure for a magnetic recording medium, wherein the bumps are arranged at an average interval of 25 μm in both the radial direction and the circumferential direction. 2. The height of the bump is 10 to 2 after the magnetic recording medium has passed through the manufacturing steps of sputtering and lubrication.
2. The low static friction laser bump structure for a magnetic recording medium according to claim 1, wherein the thickness is in a range of 7 nm. 3. The low static friction laser bump structure for a magnetic recording medium according to claim 2, wherein the bump height is 18 nm. 4. The low static friction laser bump structure for a magnetic recording medium according to claim 2, wherein the bump height is 20 nm. 5. The low static friction laser bump structure for a magnetic recording medium according to claim 1, wherein any two adjacent bumps are arranged with an interval of 30 μm or more on average. 6. The low static friction laser bump structure for a magnetic recording medium according to claim 1, wherein any two adjacent bumps are arranged with an interval of 35 μm or more on average. 7. The low static friction laser bump structure for a magnetic recording medium according to claim 1, wherein said annular edge has a diameter of 4.5 to 7 μm. 8. The low static friction laser bump structure for a magnetic recording medium according to claim 1, wherein said annular edge has a diameter of 6.3 μm.