Disk drive slider design for thermal fly-height control and burnishing-on-demand
View Patent ↗An embodiment of the invention is a slider with a lift pad and a thermal protrusion pad in which the heads are located. The lift pad is located immediately in front of the thermal protrusion pad and is designed to achieve the flying characteristics needed for normal operation of the disk drive. The thermal protrusion pad includes a heater which is used to protrude the pad for burnishing-on-demand and/or for thermal fly-height control. The thermal protrusion pad is designed to generate very little lift so that protruding the thermal protrusion pad does not significantly increase the lift experienced by the slider. An alternative embodiment uses two overcoat thicknesses on the ABS surface with the thermal protrusion pad having a thin overcoat and the lift pad having a thicker overcoat.
1. A disk drive comprising:
a slider with at least one heater in an electrical circuit, the heater being disposed to heat a thermal protrusion pad, with dimensions from 5 to 50 microns, containing a read sensor located on a trailing edge of the air-bearing surface of the slider, the slider having a lift pad located in front of the thermal protrusion pad, the lift pad and the thermal protrusion pad being separated by a trench and the lift pad having a shape that creates lift, and the thermal protrusion pad creating a negligible amount of lift, whereby lift is not significantly increased when the heater heats the thermal protrusion pad causing the thermal protrusion pad to protrude; and
a control system which selectively varies power to the heater to induce a variable protrusion of the thermal protrusion pad to adjust a fly height of the slider during read operations.
2. The disk drive of claim 1 wherein the lift pad has a front wall disposed at a shallow angle of approximately from 0.1 to 6 degrees from a plane of the air-bearing surface.
3. The disk drive of claim 1 wherein the lift pad has a step height of approximately 0.05 to 0.5 microns.
4. The disk drive of claim 1 wherein the lift pad is wider in a direction perpendicular to a direction of airflow than a direction parallel to the direction of airflow.
5. The disk drive of claim 4 wherein the lift pad in a plan view has symmetrical lift-generating features on a left and right side of the lift pad, the lift-generating features protruding outward toward the front of the slider.
6. The disk drive of claim 1 further comprising a lift pad pedestal on which the lift pad is formed, a top surface of the lift pad pedestal being recessed from a top surface of the lift pad, the top surface of the lift pad pedestal extending from the lift pad toward the front of the slider.
7. The disk drive of claim 6 wherein a front wall of the lift pad pedestal is disposed at an angle greater than approximately 10 degrees from horizontal.
8. A disk drive comprising:
a slider with at least one heater in an electrical circuit, the heater being disposed to heat a thermal protrusion pad containing a read sensor located on a trailing edge of the air-bearing surface of the slider, the slider having a lift pad located in front of the thermal protrusion pad and having a shape that creates lift, and the thermal protrusion pad creating a negligible amount of lift, whereby lift is not significantly increased when the heater heats the thermal protrusion pad causing the thermal protrusion pad to protrude; and
a control system which selectively controls power to the heater to induce a variable protrusion of the slider; and
wherein the control system includes a burnishing procedure which applies power to the heater to protrude the thermal protrusion pad to force the thermal protrusion pad into contact with the disk surface while rotating the disk to burnish the thermal protrusion pad by removing at least a portion of material from the thermal protrusion pad.
9. The disk drive of claim 8 wherein the burnishing procedure removes an overcoat from the read sensor.
10. A disk drive comprising:
a slider with at least one heater in an electrical circuit, the heater being disposed to heat a thermal protrusion pad containing a read sensor located on a trailing edge of the air-bearing surface of the slider, the slider having a lift pad located in front of the thermal protrusion pad and having a shape that creates lift, and the thermal protrusion pad creating a negligible amount of lift, whereby lift is not significantly increased when the heater heats the thermal protrusion pad causing the thermal protrusion pad to protrude; and
a control system which selectively controls power to the heater to induce a variable protrusion of the slider; and
wherein the lift pad and the thermal protrusion pad are separated by a trench etched into a substrate and a wall of the thermal protrusion pad forming one side of the trench is disposed at a steep angle and a top surface of the thermal protrusion pad is flat so that lift is not created when the thermal protrusion pad protrudes when heated.
11. The disk drive of claim 10 wherein the trench has a depth greater than 0.5 microns.
12. The disk drive of claim 10 wherein the trench has a width from 10 to 100 microns.
13. A disk drive comprising:
a slider with at least one heater in an electrical circuit, the heater being disposed to heat a thermal protrusion pad containing a read sensor located on a trailing edge of the air-bearing surface of the slider, the slider having a lift pad located in front of the thermal protrusion pad and having a shape that creates lift, and the thermal protrusion pad creating a negligible amount of lift, whereby lift is not significantly increased when the heater heats the thermal protrusion pad causing the thermal protrusion pad to protrude; and
a control system which selectively controls power to the heater to induce a variable protrusion of the slider; and
wherein the lift pad has an overcoat layer with a first thickness and the thermal protrusion pad has an overcoat layer with a second thickness which is less than the first thickness.