Magnetic heads for use in different fluid atmospheres, and related methods
Described are magnetic recording heads that include an air-bearing surface and that are designed to be useful or potentially useful in two or more different types of fluid atmospheres; also described are related methods of testing the magnetic recording heads and installing the magnetic recording heads in a hard disk drive, as well as hard disk drives that contain a magnetic recording head as described.
1. A magnetic recording head comprising:
an air-bearing surface that includes an upper surface, multiple recessed surfaces of different depths relative to the upper surface, a leading edge, a trailing edge, a longitudinal axis between the leading edge and the trailing edge, and longitudinal curvature;
a center pad region positioned toward the trailing edge, the center pad region comprising:
a recessed center pad portion defined on opposed sides by opposed first and second center pad rails that extend in a length-wide direction, and defined on a trailing edge side by a back rail extending between the first and second center pad rails,
a center pad extending from the back rail at least partly into the recessed center pad portion in a direction toward the leading edge,
a first center, pad channel between the center pad and the first center pad rail on a leading edge side of the back rail and a trailing edge side of the recessed center pad portion, and
a second center pad channel between the center pad and the second center pad rail on a leading edge side of the back rail and a trailing edge side of the recessed center pad portion,
the first center pad channel and the second center pad channel located on opposed sides of the center pad and spaced not more than 22 microns apart, and the first center pad channel and the second center pad channel each independently having a width of from 5 to 20 microns; and
an embedded transducer positioned toward the trailing edge proximate to the central longitudinal axis.
2. A magnetic recording head of claim 1 , the first and second center pad channels each having a depth in a range from 0.1 to 0.3 micron relative to the upper surface.
3. A magnetic recording head of claim 1 wherein the first center pad channel and the second center pad channel each have a width in a range from 7 to 15 microns.
4. A magnetic recording head of claim 1 wherein the center pad channels are separated in the width direction by a distance of less than 20 microns.
5. A magnetic recording head of claim 1 wherein the upper surface includes a surface of the center pad, a surface of the back rail, surfaces of the first and second center pad rails, and surfaces of two or more pressure pads.
6. A magnetic recording head of claim 1 comprising the center pad and four additional pressure pads at the upper surface.
7. A magnetic recording head of claim 1 wherein the recessed surfaces have depths relative to the upper surface that include: a first depth (D1), a pre-maximum depth (D pre-max ) deeper than the first depth, and a maximum depth (D max ) deeper than the pre-maximum depth, with no recessed surface having a depth between the pre-maximum depth and the maximum depth, and a difference between the maximum depth and the pre-maximum depth is less than 2.0 microns.
8. A magnetic recording head of claim 7 wherein the maximum depth is less than 3.5 microns.
9. A magnetic recording head of claim 1 wherein the recessed surfaces are formed by, a series of three etching steps:
the first etching step (“mill 1”) removed an amount of material in a depth direction of not more than 0.3 microns,
the second etching step (“mill 2”) removed an amount of material in a depth direction of not more than 1.0 micron,
the third etching step (“mill 3”) removed an amount of material in a depth direction of not more than 2.0 microns.
10. A magnetic recording head of claim 1 wherein the longitudinal curvature comprises a crown height in a range from 0.4 to 0.7 microinches.
11. A magnetic recording head of claim 1 wherein the magnetic recording head:
can achieve an active pressure at a center channel of at least 35 atmospheres in a helium atmosphere, and
can achieve an active pressure at a center channel of at least 35 atmospheres in an air atmosphere.
12. A magnetic recording head of claim 1 wherein
the magnetic recording head is capable of being used in a helium atmosphere at a fly height in a range of from 7 to 12 nanometers, and
the magnetic recording head is capable of being used in an air atmosphere at a fly height in a range of from 7 to 12 nanometers.
13. A hard disk drive comprising a magnetic recording head of claim 1 , the hard disk drive having an interior that contains concentrated helium.
14. A hard disk drive comprising a magnetic recording head of claim 1 , the hard disk drive having an interior that contains an air atmosphere.