U.S. patent application number 13/306537 was filed with the patent office on 2012-03-22 for magnetic media formed by a thin planar arbitrary gap pattern magnetic head.
This patent application is currently assigned to Advanced Research Corporation. Invention is credited to Matthew P. Dugas.
Application Number | 20120069473 13/306537 |
Document ID | / |
Family ID | 40578257 |
Filed Date | 2012-03-22 |
United States Patent
Application |
20120069473 |
Kind Code |
A1 |
Dugas; Matthew P. |
March 22, 2012 |
MAGNETIC MEDIA FORMED BY A THIN PLANAR ARBITRARY GAP PATTERN
MAGNETIC HEAD
Abstract
Magnetic media made using planar magnetic heads. A head may
comprise a substrate having conductive thru-hole vias extending
therethrough, a first magnetic layer deposited and patterned on the
substrate, a first insulation layer deposited and patterned on the
first magnetic layer, a conductive coil layer deposited and
patterned on the first insulation layer and connected to the
conductive thru-hole vias, a second insulation layer deposited and
patterned on the conductive coil layer, vias patterned into the
insulation layer extending to the first magnetic layer, a second
magnetic layer deposited in the vias, and a third magnetic layer
deposited and patterned on the second insulation layer and second
magnetic layer. The third magnetic layer may be connected to the
first magnetic layer through the second magnetic layer deposited in
the vias of the insulation layers.
Inventors: |
Dugas; Matthew P.; (St.
Paul, MN) |
Assignee: |
Advanced Research
Corporation
|
Family ID: |
40578257 |
Appl. No.: |
13/306537 |
Filed: |
November 29, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12414607 |
Mar 30, 2009 |
8068301 |
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13306537 |
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12414611 |
Mar 30, 2009 |
8068302 |
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12414607 |
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12414604 |
Mar 30, 2009 |
8068300 |
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12414611 |
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61040373 |
Mar 28, 2008 |
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61040373 |
Mar 28, 2008 |
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61040373 |
Mar 28, 2008 |
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Current U.S.
Class: |
360/134 ;
360/131; G9B/5.289; G9B/5.291 |
Current CPC
Class: |
G11B 5/3183 20130101;
G11B 5/00826 20130101; G11B 5/29 20130101; G11B 5/3163
20130101 |
Class at
Publication: |
360/134 ;
360/131; G9B/5.289; G9B/5.291 |
International
Class: |
G11B 5/74 20060101
G11B005/74; G11B 5/78 20060101 G11B005/78 |
Claims
1. Magnetic media comprising a plurality of servo tracks, each
servo track having a unique servo track ID encoded in the magnetic
transitions of the servo track.
2. The magnetic media of claim 1, wherein a plurality of magnetic
transitions of the servo track form a timing-based servo
pattern.
3. Magnetic media formed by a magnetic recording head comprising: a
substrate having a substantially continuous surface generally
parallel with a tape bearing surface; and a plurality of
independent and magnetically isolated channels, each comprising: a
first magnetic layer deposited on the substantially continuous
surface of the substrate; an electrically conductive coil layer
deposited on the first magnetic layer; and a second magnetic layer
deposited on the electrically conductive coil layer, the second
magnetic layer comprising at least one magnetic gap pattern.
4. The magnetic media of claim 3, wherein the first and second
magnetic layers of one or more of the channels are separated from
their respective electrically conductive coil layer by at least one
insulating layer.
5. The magnetic media of claim 3, wherein the first and second
magnetic layers of one or more of the channels are connected
forming a closed magnetic flux path.
6. The magnetic media of claim 4, wherein the first and second
magnetic layers of the one or more channels are connected through
vias in the insulating layers to form a closed magnetic flux
path.
7. The magnetic media of claim 4, wherein the substrate comprises a
plurality of conductive thru vias.
8. The magnetic media of claim 7, wherein the electrically
conductive coil layer of one or more channels extends from and
connects a first conductive thru via to a second conductive thru
via associated with the respective channel.
9. The magnetic media of claim 3, wherein the at least one magnetic
gap pattern comprises a timing-based magnetic gap pattern.
10. The magnetic media of claim 8, wherein two or more of the
channels are driven independently of one another and at least one
of the servo bands of the magnetic media has a unique servo track
ID encoded in the magnetic transitions of the servo band.
11. Magnetic tape media comprising: a plurality of data bands; and
a plurality of servo bands, each having a timing-based servo
pattern written thereon by a magnetic recording head comprising: a
substrate having a substantially continuous surface generally
parallel with a tape bearing surface; and a plurality of
independent and magnetically isolated channels, each comprising: a
first magnetic layer deposited on the substantially continuous
surface of the substrate; an electrically conductive coil layer
deposited on the first magnetic layer; and a second magnetic layer
deposited on the electrically conductive coil layer, the second
magnetic layer comprising at least one magnetic gap pattern.
12. The magnetic tape media of claim 11, wherein at least two of
the plurality of servo bands are written independently of one
another.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of priority to U.S. Ser. No.
61/040,373 filed Mar. 28, 2008, the contents of which are herein
incorporated by reference.
FIELD OF THE INVENTION
[0002] The present disclosure relates to magnetic media. More
particularly, the present disclosure relates to magnetic media
using thin film planar arbitrary gap pattern magnetic recording
heads.
BACKGROUND OF THE INVENTION
[0003] Prior art magnetic heads are disclosed in U.S. Pat. No.
6,947,256 ("'256 Patent"), titled "Embedded Wire Planar Write Head
System and Method," issued to Biskebom, Doscher, and Eaton, U.S.
Pat. No. 7,322,096 ("'096 Patent"), which is a divisional of the
'256 Patent, also titled "Embedded Wire Planar Write Head System
and Method," and issued to Biskeborn, Doscher, and Eaton, and U.S.
Pat. No. 7,119,976 ("'976 Patent"), titled "Planar Servo Format
Verifier Head," issued to Biskeborn, Kirschenbaum, and Taylor. A
characteristic of these prior art heads is beginning fabrication of
the head with a trenched substrate, the trench being made into a
nonmagnetic substrate, and the fabrication of the head proceeding
thereupon with thin film processing. The trenched substrate is
subsequently filled in so that the final plane of the recording
head is substantially close to the plane of the originating
substrate with the trench being filled in with much of the head
structure.
[0004] FIGS. 1A and 1B illustrate a prior art magnetic write head
of the type disclosed in the '256 Patent. The '256 Patent discloses
building a head from a substrate 406 into which a trench has been
made. For the single gap set head 400, the head is fabricated by
depositing thin film layers into the trench. For each set of gaps
500, made up of arrays of discrete gaps 411 and 413 spanning the
width of the tape, there is a single coil layer 410 running beneath
the set of gaps 500. The coil layer 410 spans from one edge of the
head to the other, parallel to the tape bearing surface, but the
longitudinal axis and current flow of the coil layer 410 is
perpendicular to the tape's velocity direction.
[0005] In FIGS. 2A and 2B, the '256 Patent further illustrates
tandem head structures 900 and 1200 made from two pockets patterned
into the insulating layer in a single trench 906. This embodiment
has two coils, one for each pocketed head element 902, 904 (FIG.
2A) or 1202, 1204 (FIG. 2B). This embodiment allows for two head
elements 902, 904 (FIG. 2A) or 1202, 1204 (FIG. 2B), each of which
are functionally identical to single head element 400 but which are
displaced in the down-track direction with respect to each other.
Each of the two coil layers, i.e., 1208, 1210, drives a uniquely
associated set of gaps, i.e., write gaps 1206 of first head element
1202 and write gaps 1206 of second head element 1204, respectively,
that are staggered from one another in the down-track direction to
accommodate the necessary conducting circuit 1208, 1210 that spans
from one end of the slider to the other, beneath the associated gap
set.
[0006] In FIG. 2C, the '256 Patent illustrates another embodiment
1000 based on a further down-track staggered gap and down-track
staggered coil expansion of embodiment 900. In this embodiment
1000, a generalization of embodiment 900 is called out so that more
gaps 1004 can be driven independently. In all of the above
embodiments, the gaps are shown to be driven by a coil layer that
spans from one edge of the slider to the other, each coil driving
an associated set of gaps and each coil starting on one end of the
slider body and ending on the other end. In the generalized
embodiment, the gaps 1004 are aligned in a staggered formation to
accommodate the necessary conducting circuits, and magnetic
circuit, one circuit for each gap or gap set, and hence the gaps
can only be written independently if they are staggered to
accommodate the associated magnetic circuit and associated
electrical conducting circuit.
[0007] The '096 Patent further discloses and teaches the same
subject matter as the above described planar head built from a
trenched substrate. The '976 Patent discloses a second trench for
accommodation of the lead for a servo read head element and a
formatting system for using such a head. This prior art embodiment
is illustrated in FIG. 3.
[0008] The prior art only teaches planar heads built from a
trenched substrate. Trenched substrate based heads lead to a
natural result of air skiving edged, flat contour sliders that are
velocity independent. However, the limited multichannel embodiments
of the prior art have fabrication limitations and interconnect
issues that are not fully addressed. In the independently written
multi-channel embodiments, each channel is a full width trench head
that is merely displaced in the down-track direction from one
another. As such, seventeen such channels, for example, would
require seventeen trenched heads displaced sixteen times in the
down-track direction from one another. The resulting head-to-media
interface would have an extremely wide media scrub zone that would
mitigate the elegance of the air skiving single trench head.
[0009] Thus, there exists a need in the art for an easily
manufactured planar magnetic head, particularly for tape servo
format writing and verification, and more particularly for
multi-channel embodiments with a narrow scrub path single bump
interface. There is a need in the art for a method of making a
planar magnetic head using a built-up approach on planar substrate,
as opposed to deposition and lithography in a trenched substrate,
to achieve a true planar head. There is a further need in the art
for a method of making a planar magnetic head using thru-hole via
technology to connect the leads to a conductive coil layer. There
is a further need in the art for an easily manufactured planar
magnetic head having independent channels without each gap set
having to be displaced or staggered in the down-track
direction.
BRIEF SUMMARY OF THE INVENTION
[0010] The present disclosure, in one embodiment, relates to a
magnetic head for magnetic tape. The magnetic head may include a
substrate having a substantially continuous surface generally
parallel with a tape bearing surface of the magnetic head. A first
magnetic layer may be deposited on the substantially continuous
surface of the substrate. An electrically conductive coil layer is
deposited on the first magnetic layer. A second magnetic layer may
be deposited on the electrically conductive coil layer. The second
magnetic layer may include one or more magnetic gap patterns. In
further embodiments, the first and second magnetic layers may be
separated from the electrically conductive coil layer by insulating
layers. Additionally, the first and second magnetic layers may be
connected through vias in the insulating layers to form a closed
magnetic flux path.
[0011] The present disclosure, in another embodiment, relates to a
method of making a magnetic head. The method may include providing
a substrate having a substantially continuous surface generally
parallel with a tape bearing surface of the magnetic head,
providing a first magnetic layer on the substantially continuous
surface of the substrate, providing an electrically conductive coil
layer on the first magnetic layer, and providing a second magnetic
layer on the electrically conductive coil layer. In other
embodiments, a full single turn may be used or multiple turns may
be used. The second magnetic layer may include one or more magnetic
gap patterns. Electrically conductive vias may be provided that
extend through the substrate and contact the conductive coil layer.
In other embodiments, the leads may be brought to the edge of the
slider body. In further embodiments, a first insulation layer may
be provided between the first magnetic layer and the electrically
conductive coil layer, and a second insulation layer may be
provided between the electrically conductive coil layer and the
second magnetic layer. Vias, connecting the first and second
magnetic layers, may further be provided in the insulating layers
to form a closed magnetic flux path.
[0012] The present disclosure, in a further embodiment, relates to
magnetic media and/or formatted magnetic tape cartridges, which
contain a media format particular to a planar magnetic head in
accordance with the present disclosure, and particularly to a
planar magnetic head having independent addressable channels. The
present disclosure further relates to a method of formatting and or
verifying magnetic media and/or magnetic tape cartridges using a
write/read magnetic head in accordance with the present
disclosure.
[0013] While multiple embodiments are disclosed, still other
embodiments of the present invention will become apparent to those
skilled in the art from the following detailed description, which
shows and describes illustrative embodiments of the invention. As
will be realized, the invention is capable of modifications in
various obvious aspects, all without departing from the spirit and
scope of the present invention. Accordingly, the drawings and
detailed description are to be regarded as illustrative in nature
and not restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] While the specification concludes with claims particularly
pointing out and distinctly claiming the subject matter that is
regarded as forming the present invention, it is believed that the
invention will be better understood from the following description
taken in conjunction with the accompanying Figures, in which:
[0015] FIG. 1A is a cross-sectional view of a prior art magnetic
head.
[0016] FIG. 1B is a perspective view of another prior art magnetic
head.
[0017] FIG. 2A is a cross-sectional view of a prior art magnetic
write head with two staggered coil circuits and two staggered gap
sets.
[0018] FIG. 2B is a perspective view of a prior art magnetic write
head with two staggered coil circuits and two staggered gap sets,
resulting in essentially two staggered heads made into a common
trench.
[0019] FIG. 2C is a perspective view of a prior art magnetic write
head with an arbitrary array of staggered gaps and staggered coils,
resulting in essentially a large number of staggered heads made
into a common trench.
[0020] FIG. 3 is a cross section view of a prior magnetic read
head.
[0021] FIG. 4A is a perspective view of a multichannel magnetic
head in accordance with an embodiment of the present
disclosure.
[0022] FIG. 4B is a close up perspective view of one of the head
channels of the multichannel magnetic head shown in FIG. 4A.
[0023] FIG. 4C is a close-up perspective view of one of the head
channels of another embodiment of a multichannel magnetic head
having a different lead configuration.
[0024] FIG. 5 is a perspective view of a multichannel magnetic head
in accordance with an embodiment of the present disclosure that is
placed into a slider body.
[0025] FIG. 6 is a flow chart of a method of making a magnetic head
in accordance with one embodiment of the present disclosure.
[0026] FIG. 7 is a perspective view of a substrate wafer in
accordance with an embodiment of the present disclosure.
[0027] FIG. 8 is a perspective view of a single head channel of a
multichannel head having thru-hole vias prepared in the substrate,
the thru-hole vias having electrically conductive material
deposited therein in accordance with an embodiment of the present
disclosure.
[0028] FIG. 9 is a perspective view of a single head channel of a
multichannel head having a first magnetic layer deposited and
patterned on top of the substrate in accordance with an embodiment
of the present disclosure.
[0029] FIG. 10 is a perspective view of a single head channel of a
multichannel head having a first insulation layer deposited and
patterned on top of the first magnetic layer and substrate in
accordance with an embodiment of the present disclosure.
[0030] FIG. 11A is a perspective view of a single head channel of a
multichannel head having a coil conductor layer deposited and
patterned on top of the first insulation layer in accordance with
an embodiment of the present disclosure.
[0031] FIG. 11B is a perspective view of a single head channel of a
multichannel head having a coil conductor layer deposited and
patterned on top of the first insulation layer in accordance with
another embodiment of the present disclosure.
[0032] FIG. 12A is a perspective view of a single head channel of a
multichannel head having a second insulation layer deposited over
the coil conductor layer, first insulation layer, first magnetic
layer, and substrate in accordance with an embodiment of the
present disclosure.
[0033] FIG. 12B is a perspective view of a single head channel of a
multichannel head having a second insulation layer deposited over
the coil conductor layer, first insulation layer, first magnetic
layer, and substrate in accordance with another embodiment of the
present disclosure.
[0034] FIG. 13 is a perspective view of a single head channel of a
multichannel head having vias provided in the second insulation
layer.
[0035] FIG. 14 is a perspective view of a single head channel of a
multichannel head having a second magnetic layer deposited in the
vias and creating magnetic subpoles to form a closed magnetic path
in accordance with an embodiment of the present disclosure.
[0036] FIG. 15 is a perspective view of a single head channel of a
multichannel head having a third magnetic layer deposited on top of
the second magnetic layer and second insulation layer in accordance
with an embodiment of the present disclosure.
[0037] FIG. 16A is a perspective view of a single head channel of a
multichannel head having a gap pattern formed in the third magnetic
layer, wherein the third magnetic layer is further patterned to
provide magnetic isolation from channel to channel in accordance
with an embodiment of the present disclosure.
[0038] FIG. 16B is a perspective view of a single head channel of a
multichannel head having a gap pattern fanned in the third magnetic
layer, wherein the third magnetic layer is further patterned to
provide magnetic isolation from channel to channel in accordance
with another embodiment of the present disclosure.
[0039] FIG. 17 is a detailed perspective cross-sectional view, in
the cross-track direction, of a channel of a magnetic head in
accordance with an embodiment of the present disclosure.
[0040] FIG. 18 is a detailed perspective cross-sectional view, in
the down-track direction, of a channel of a magnetic head in
accordance with one embodiment of the present disclosure.
[0041] FIG. 19A is a top view of a magnetic head having a
two-dimensional array of channels in accordance with an embodiment
of the present disclosure.
[0042] FIG. 19B is a top view of a magnetic head having a
two-dimensional array of channels in accordance with another
embodiment of the present disclosure.
[0043] FIG. 20 is a schematic view of a standard LTO format.
[0044] FIG. 21 is a top view of a data band between two servo
bands.
[0045] FIG. 22 is a top view of two servo bands encoded unique data
in the servo pulse groups using a magnetic head in accordance with
one embodiment of the present disclosure.
[0046] FIG. 23 is a schematic view of a tape transport system in
accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION
[0047] The present disclosure relates to novel and advantageous
magnetic recording heads and methods of making the same.
Particularly, the present disclosure relates to novel and
advantageous planar magnetic heads and methods of making planar
magnetic heads using a built-up approach to achieve a true planar
head. Furthermore, the present disclosure, in one of its
embodiments, relates to a novel and advantageous method of making a
planar magnetic head using thru-hole via technology to connect the
leads to a conductive coil layer. In one embodiment, a magnetic
head may comprise a substrate having conductive thru-hole vias
extending through the substrate, a first magnetic layer deposited
and patterned on the substrate, a first insulation layer deposited
and patterned on the first magnetic layer, a conductive coil layer
deposited and patterned on the first insulation layer, a second
insulation layer deposited and patterned on the conductive coil
layer, vias patterned or etched into the insulation layers
extending to the first magnetic layer, a second magnetic layer
deposited in the vias, and a third magnetic layer deposited and
patterned on the second insulation layer and second magnetic layer.
The third magnetic layer may be connected to the first magnetic
layer through the second magnetic layer deposited in the vias of
the insulation layers. The present disclosure further relates to
magnetic media made by the various embodiments of heads of the
present disclosure.
[0048] In regards to descriptions of magnetic and nonmagnetic
materials, terms such as "nonmagnetic materials" and "magnetically
impermeable materials" are meant to mean materials with a
substantially or very low magnetic permeability approaching that of
free space, which is of unit permeability. As magnetic fields
permeate free space and all materials with the exception of
superconductors and perfect diamagnetic materials, the practical
concept of using high permeability or magnetically soft materials
for the active recording head elements is juxtaposed to the use of
nonmagnetic or magnetically impermeable materials for other parts
of the device and the meaning should be made clear from the
discussion and context provided herein.
[0049] In the figures that follow, some may be considered wafer
level illustrations and other may be considered row bar or device
level illustrations. In regards to the process illustrations which
are predominately wafer level illustrations, the figures may also
reveal the row bar level or device level sections and borders, so
as to provide clarity.
[0050] FIGS. 4A, 4B and 4C illustrate an embodiment of a
multichannel magnetic head 40 in accordance with the present
disclosure. In FIGS. 4A, 4B, and 4C, the head contour is flat and
there is no slider body. In other embodiments, the head 40 may have
a different contour, such as a curved, or cylindrical contour. FIG.
4A illustrates the completed head in a five-channel format with
channels or bands 42A through 42E, and collectively and
individually referred to as 42, with each of the five channels 42
having independent leads. While FIG. 4A illustrates five
independently addressable channels 42A-42E, it is recognized that
any suitable number of channels 42 may be employed, such as fewer
or greater than five channels. Each of the channels may have the
same or different signals impressed. The channels may be connected
in series, parallel, or series-parallel in such common signal
applications. Such signal may have a common phase or may be made to
have a relative phase delay. Each of the independent channels 42
may have a gap configuration consisting of typically two gap lines.
However, any combination of gap lines may be used, such as a single
gap line or three or more gap lines per head channel. FIG. 4B
illustrates a close up perspective view of a head channel, e.g.,
42C, and the surrounding area, the head channel 42C having a pair
of angled gaps 45. The external leads 46 illustrated in FIG. 4B are
an electrical extension of the substrate thru-via leads, discussed
in further detail below. These external leads 46, of FIGS. 4A and
4B, are shown for illustrative purposes only and can also represent
solder or gold or alloy bumps that could form a direct bonded
connection to a rigid lead assembly or flex circuit. Each of the
channels 42 may be driven simultaneously or independently. Each of
the channels 42 of magnetic recording head 40 may have individual
coil layers with associated coil leads, as described in further
detail below, such that each of the channels 42 may be driven
independently with the same or different signals, as required for
the format being written.
[0051] In another embodiment, as illustrated in FIG. 4C, the leads
may be made to wrap around the edge of the head 40. In this
embodiment, the side plane 49 of the head 40 may be lapped to
reveal the planar surface coil and sputter or plate the edge leads
47 such that they make electrical connection to the edge revealed
surface coil. The edge leads 47 may terminate in larger pad areas,
as shown. The leads 47 may then be made to have contact with
external circuitry by means of, for example but not limited to, a
flex circuit, wire bonds, or soldered solid wire. Each of the
channels 42 may be driven simultaneously or independently. Each of
the channels 42 of magnetic recording 40 may have individual coil
layers with associated coil leads, as described in further detail
below, such that each of the channels 42 may be driven
independently with the same or different signals, as required for
the format being written.
[0052] An embodiment of this head placed into an external slider
body 50 is illustrated in FIG. 5. In alternative embodiments, the
head 40 can comprise its own independent slider body, and an
external slider body 50 may not be used. The external slider body
50 may be suitably made for a cylindrical contour head or a flat
contour head. The external slider body 50 may have air bleed slots
and/or skiving edges. The external slider body 50 may be made of a
common hard ceramic, such as but not limited to bi-crystal poly
crystal N58 AlTiC or poly-crystal Al203, or may be made of single
crystal sapphire, the latter allowing for transparency and direct
optical observation of the head-to-tape interface. All of the above
described slider systems are not limiting and other slider systems
may be used without departing from the spirit and scope of the
present disclosure.
[0053] FIG. 6 is a flow chart for a method 600 of making a magnetic
head 40 according to one embodiment of the present disclosure. The
steps illustrate a method of making a head 40 having a single strip
line coil. However, a full coil turn or multiple coil turns are
considered fully within the spirit and scope of the present
disclosure; these embodiments may include more method steps and may
result in a more efficient head. The method steps are not limiting
and are not meant to be complete or exhaustive. In some
embodiments, some of the steps may be excluded and other steps may
be included without departing from the spirit and scope of the
present disclosure.
[0054] In step 605, and as illustrated in FIG. 7, a wafer level
substrate 72 having a substantially continuous surface generally
parallel with a tape bearing surface of the magnetic head 40 may be
provided. Head row bar 74 is shown as a section of the wafer. The
substrate 72 may be prepared having thru-hole vias 82 (shown in
FIG. 8) for coil conducting leads. Alternatively, as discussed with
reference to FIG. 4C, the leads may run to the edge of the head
slider in the down-track direction and can be made to run over the
edge of the slider and wrap around the corner by matching with
leads running on the vertical face of the slider, and may
subsequently be attached to flex or wire leads. Such an edge
connection technique can offer an alternative to a thru-hole via
technique. Alternatively, the leads may be run in the cross-track
direction past the region of the tape bearing surface, and connect
to pads so as to avoid interfering with the tape path, or they
could wrap around these other perpendicular cross-track edges, as
just discussed. Illustration of a substrate 72 wafer in FIG. 7 is
not limiting, and a magnetic head 40 of the present disclosure may
be manufactured at a wafer level or row bar level without departing
from the spirit and scope of the present disclosure. In some
embodiments, manufacturing at a wafer level may be preferred due to
manufacturing efficiencies, and may further be preferred for flat
head contours. In one embodiment, the wafer substrate 72 may
comprise a silicon wafer, as the silicon wafer may easily have the
vertical thru-hole vias prepared using the well known "Bosch"
process, for example, and thus the process of making the vias can
be a wafer level process. Another process for etching thru-hole
vias is that of an anisotropic KOH wet etch. When using a
semiconductor material such as silicon for the substrate, an
initial non-conducting layer may be used to insulate the current
leads so that the silicon does not electrically short the lead.
Such insulating layers could be SiO2 or SiN, among other suitable
materials. Similarly, insulating layers may be used so that the
conductor-filled vias, described in detail below, will not be
shorted by the semiconductor material.
[0055] Various techniques of connecting through the substrate may
be considered fully within the scope of the disclosure. In regards
to using KOH as a selective etch, if SiN is used as the first
insulating layer of the planar device formation, this may also be
used as an etch stop for KOH wet etching. In the latter embodiment,
it is envisioned that the KOH thru-hole via etch could be used in a
back-end process step.
[0056] In another embodiment, an insulating material may be used as
the substrate. One such choice would be sapphire or other
insulating technical ceramic, such as but not limited to zirconium
oxide, alumina, calcium titanate, barium titanate, etc., each of
which is commercially available in bulk or wafer form.
[0057] In yet another embodiment, the vias can be machined with
high speed drilling techniques. This is a serial process and can be
more expensive. However, with a non-conductive substrate, the
subsequent oxidizing or insulating step is not required, mitigating
the machining expense of a technical ceramic insulating substrate.
Also, such materials are far harder than silicon and hence are
mechanically more stable as a head slider body. Thus, a substrate,
such as single crystal alumina, is entirely within the spirit and
scope of the present disclosure and may offer many mechanical and
electrical advantages.
[0058] As further shown in detail in FIG. 8, thru-hole vias 82
extend to the underside of the substrate 72. FIG. 8 may be
considered a section of the wafer but can also represent a section
of a head row bar. As stated above, a magnetic head 40 of the
present disclosure may be manufactured at a wafer level or row bar
level without departing from the spirit and scope of the present
disclosure. A row bar may represent a single head row or may be
multiple heads all in the same row. The length of the row bar cut
from the wafer is a matter of choice or design in the manufacturing
process. In one embodiment, there are two thru-hole vias 82
prepared in the substrate 72 for each channel. Other coil
configurations, such as center tapped and magneto-resistive leads,
may be considered and are within the spirit and scope of the
present disclosure. Such coil configurations may require more leads
per channel and therefore may involve more process steps. As
illustrated in FIG. 8, an electrically conductive material 84 may
be plated into, or otherwise placed into, the thru-hole vias 82,
resulting in electrically conductive leads 86. In one embodiment,
the electrically conductive material 84 may be copper. In other
embodiments, the electrically conductive material 84 may be any
other suitable electrically conductive material.
[0059] In step 610, and as illustrated in FIG. 9, a first, or
bottom, magnetic layer 92 may be deposited and patterned on top of
the substrate 72. The first magnetic layer 92 may comprise NiFe or
other suitable magnetically permeable material or materials. In one
embodiment, as shown in FIG. 9, the conductive leads 86 are
entirely exposed and uncovered by the patterned first magnetic
layer 92. The first magnetic layer 92 may be patterned according to
a specific head design and/or requirement. The first magnetic layer
92 may comprise the bottom magnetic yoke of a magnetic circuit for
the magnetic head 40.
[0060] In step 620, and as illustrated in FIG. 10, in one
embodiment, a first insulation layer 102 may be deposited and
patterned on top of the first magnetic layer 92 and substrate 72.
In one embodiment, the first insulation layer 102 may comprise a
nonmagnetic material. In one embodiment, as shown in FIG. 10, the
conductive leads 86 may be entirely exposed and uncovered by the
first insulation layer 102. The first insulation layer 102 may be
patterned according to a specific head design and/or requirement.
In a further embodiment, the first insulation layer 102 may be
planarized. The first insulation layer 102 forms an insulating
barrier for a subsequent coil layer. In alternative embodiments, a
first insulation layer 102 may not be used, and the step of
depositing and patterning the first insulation layer 102 may be
eliminated. In such embodiments, the coil current will also run
through the magnetic material.
[0061] In step 630, and as illustrated in FIG. 11A, a coil
conductor layer 112 is deposited and patterned on top of the first
insulation layer 102. The coil conductor layer 112, in one
embodiment, may be copper. In other embodiments, the coil conductor
layer 112 may be any other suitable electrically conductive
material. The coil conductor layer 112 is patterned such that it
extends over the first insulation layer 102, first magnetic layer
92, and substrate 72 from one conductive lead 86 to the other 86.
FIG. 11B shows an embodiment wherein the coil layer 112 is directed
to the edge of the row bar such that it may subsequently be
revealed and connected to edge lead 47, as shown, for example, in
FIG. 4C.
[0062] In alternative embodiments, the coil layer may be made into
two layers with one layer going beneath the first magnetic layer 92
and then coming back on top of the first magnetic layer 92 to form
a complete single-turn head. In such an embodiment, the thru-hole
vias 82 may be prepared generally adjacent to each other. The
resulting leads 86 would likewise be adjacent to one another. Such
an alternative embodiment will allow for one layer below and one
layer above the bottom magnetic yoke 92. Prior to depositing a
first magnetic layer 92, a first conductor layer may be deposited
and patterned or etched on the substrate 72. An insulator may then
be deposited and etched over the first conductor layer. The head
may then be planarized, and vias will be opened such that the
second coil layer will connect with the bottom coil layer thru one
via and then to the other lead end thru another via. Whether a
single coil layer is used, or whether a full single-turn style
coil, e.g., under and over the bottom magnetic yoke, is used will
depend on the efficiency of the head and the write driver used. In
the latter construction, the natural extension to a multi-turn
helical coil is evident and would be particularly advantageous for
an inductive read verify head or data head, each of which are
within the spirit and scope of the present disclosure. Multi-turn
helical coils can be done with no more layer processing than the
full single-turn system described and would be particularly
advantageous in a servo pattern verify inductive read head
design.
[0063] In step 640, and as illustrated in FIG. 12A, a second
insulation layer 122 may be deposited over the coil conductor layer
112, first insulation layer 102, first magnetic layer 92, and
substrate 72. The insulation layer 122 may comprise a nonmagnetic
material and may insulate the coil conductor 112 from a subsequent
upper magnetic layer. In one embodiment, the second insulation
layer 122 may be deposited across the entire surface of the
substrate 72, e.g., the entire surface of the substrate wafer. In a
further embodiment, in step 645, the second insulation layer 122
may be planarized to eliminate height differential in the tape path
and provide a planar layer of insulation on the substrate 72. The
conductive leads 86, coil conductor layer 112, first insulation
layer 102, and first magnetic layer 92 are illustrated in dashed
line in FIG. 12A, indicating the location of each beneath the
second insulation layer 122. In alternative embodiments, a second
insulation layer 122 may not be used, and the step of depositing
and patterning the second insulation layer 122 may be eliminated.
In some embodiments, both the first insulation layer 102 and the
second insulation layer 122 may not be used. In such embodiments,
there may be no insulating layers between the coil conductor layer
102 and the magnetic layers. However, in many practical situations
with current thin film materials, it will be preferred to use
insulating layers, as most magnetic materials are conductors and
having write currents inside the magnetic layers may not lead to a
well-behaved head. The situation may become even more complicated
if the recording medium is a conductive thin film. As illustrated
in another embodiment in FIG. 12B, the coil leads may be made to
terminate along the row bar boundary such that they may be exposed
and connected to edge leads 47, as shown, for example, in FIG.
4C.
[0064] In step 650, and as illustrated in FIG. 13, a via 132 may be
etched, or otherwise prepared, in the surface of the second
insulation layer 122. The via 132 may extend through the second
insulation layer 122 and first insulation layer 102 to the first
magnetic layer 92. As can be seen in FIG. 13, vias 132 may be
provided on each side of the coil conductor layer 112 and expose at
least a portion of the first magnetic layer 92.
[0065] In step 660, and as illustrated in FIG. 14, a second
magnetic layer 142 may be deposited on top of the second insulation
layer 122, and into the vias 132, thereby filling vias 132 down to
the level of the first magnetic layer and creating magnetic
subpoles 146 in the vias. The magnetic sub-poles 146 are made from
the planarized blanket film 142. The second magnetic layer 142 may
comprise NiFe or other suitable highly permeable magnetic material.
In step 665, and as illustrated in FIG. 14, the second magnetic
layer 142 may be planarized to remove extraneous magnetic material
from the surface of the second insulation layer 122 and reveal the
discrete subpoles 146 made of material 142. Planarization may be
important, in some embodiments, to remove height differential in
the tape path and provide a planar, wear-bearing surface without
undue step height differentials. The magnetic subpoles 146, e.g.,
the remaining section or component of magnetic film 142 after
planarization step 665, connect the first magnetic layer 92, or
lower magnetic yoke, to an upper magnetic film, which carries the
gap pattern(s). Alternatively, the magnetic sub-poles may be
directly plated up into the vias.
[0066] In step 670, and as illustrated in FIG. 15, a third, or
upper, magnetic layer 152 is deposited on top of the second
magnetic layer 142 and second insulation layer 122, which have been
co-planarized as shown in FIG. 14. Subpoles 146 are illustrated in
dashed line in FIG. 15, indicating the location of the subpoles 146
beneath the third magnetic layer 152. The third magnetic layer 152
may comprise NiFe or other suitable magnetically permeable
material.
[0067] As illustrated in FIG. 16A, a gap pattern 162 is etched, or
otherwise prepared, into the third magnetic layer 152 for the
magnetic head channel 42C. In other embodiments, the third magnetic
layer 152 can be plated up and around gap features made in
photoresist to form the gap pattern 162, or the gap pattern 162 may
be made into photoresist and then deposited over in a lift-off
process. The gap pattern 162 made into film layer 152 may be any
suitable timing-based or amplitude-based gap pattern or a data
write or data read gap pattern. As further illustrated in the
embodiment of FIG. 16A, the third magnetic layer 152 may further be
patterned or etched to provide magnetic isolation spaces 166 in the
magnetic layer 152, for example, from channel 42B to channel 42C of
magnetic head 40. Likewise the edge of the film 168 can be placed
on or backed away from the edge of the head row bar element 74.
Such patterning of the gaps 162 and the isolation spaces 166, 168
could also have been prepared as part of step 670 or may be done as
independent process steps, depending on the manufacturing methods
chosen. Additionally, the third magnetic layer 152 can be patterned
to define a well-behaved, flux bearing, head channel film element
167 and non-flux bearing magnetic elements 169 of the third
magnetic layer 152. Such isolation and flux confinement produces a
true multichannel magnetic head, while the flux bearing and
non-flux bearing film elements provide a substantially coplanar
tape bearing surface feature. In yet another embodiment, as
illustrated in FIG. 16B, the non-magnetic flux bearing film 169 may
be completely eliminated and etched away leaving only magnetic flux
bearing film 167 of blanket deposited thin film 152. Alternatively
the film 152 and/or film 167 and/or film 169 may be made by
selectively plating up. Further discussion of non-magnetically
energized wear pads may be found in U.S. Pat. No. 6,989,960, issued
Jan. 24, 2006, titled "Wear Pads for Timing-Based Surface Film
Servo Heads," which is hereby incorporated by reference herein in
its entirety.
[0068] As illustrated in FIGS. 16A and 16B, the channel film
element 167 may extend past the top and bottom of the gap pattern
slightly, so that the pattern does not wear prematurely at the top
and bottom. Likewise, the channel film element 167 may extend
outside the subpoles 146 toward the edge of the slider body to
provide a stable tape-bearing surface.
[0069] In other embodiments, vias 132 and the second magnetic layer
142 may not be used. In such embodiments, there may not be a
magnetic connection between the first magnetic layer 92, or bottom
magnetic yoke, and the third, or upper, magnetic layer 152. This
may result in a less efficient head, but a cheaper and easier to
build head.
[0070] FIG. 17 illustrates a detailed cross-section, in the
cross-track direction, of a channel 42C of a magnetic head 40 in
accordance with one embodiment of the present disclosure. The
cross-section features shown include the first magnetic layer 92,
the first insulation layer 102, the coil conductor layer 112, the
second insulation layer 122, and the third magnetic layer 152.
[0071] FIG. 18 illustrates a detailed cross-section, in the
down-track direction, of a channel 42C of a magnetic head 40 in
accordance with one embodiment of the present disclosure. The
cross-section features shown include the first magnetic layer 92,
the first insulation layer 102, the coil conductor layer 112, the
second insulation layer 122, the magnetic subpoles 146, and the
third magnetic layer 152.
[0072] In both cross-sectional illustrations of FIGS. 17 and 18,
the nature of the topology and the associated step heights are
shown for purposes of illustration only. The exact material
physical topology is a function of the specific process used, and
in particular, which planarization operations were performed and in
which order they were performed. One skilled in the art will
understand that the exact final process, the exact step heights,
and the topology will be a function of the exact processing
operations and process order chosen and all are to be considered
fully within the spirit and scope of the present disclosure.
[0073] In some embodiments, the magnetic head 40 may have a
generally flat contour or surface or a non-flat contour or surface.
Furthermore, the magnetic head 40 may include negative pressure
features, such as but not limited to, skiving edges or air bleed
slots. The magnetic head 40 may also include embedded tape edge
guides, such as the guides disclosed in U.S. Prov. Appl. No.
61/022,872, filed Jan. 23, 2008, titled "Apparatus and Methods for
Recording Heads with Embedded Tape Guides, Systems for Such
Recording Heads, and Magnetic Media Made by Such Recording Heads,"
which is hereby incorporated by reference herein in its
entirety.
[0074] In further embodiments, the underside of the substrate 72
may be "bumped" with conductors that connect the magnetic head 40
through its underside, for example, to a physical electrical
connector to a write driver or read back amplifier. For example, in
one embodiment, a masking layer or photoresist layer may be
deposited and patterned or etched on the underside of the substrate
72. The masking layer may be patterned such that the electrically
conductive leads 86 are at least partially exposed on the underside
of the substrate 72. An electrically conductive material, such as
but not limited to indium, gold, gold-tin eutectic, etc., may be
deposited or bumped onto the exposed electrically conductive leads
86, thereby creating conductive bumps or posts on the underside of
the substrate 72, such that the head element may be bonded to a
lead element. Similar bumping may be done on the edge connector
embodiment shown, for example, in FIG. 4C.
[0075] The various embodiments of heads of the present disclosure
and methods of making the same may be used to form a head having a
two-dimensional array of channels or magnetic heads 190, 192, such
as those illustrated in FIGS. 19A and 19B. A two-dimensional array
of channels or magnetic heads may make up a compound magnetic head,
for example, including write gaps (or write heads), read gaps (or
read heads), and/or erase gaps (or erase heads). In further
embodiments, a two-dimensional array of channels or magnetic heads
may include data read/write heads and format or servo read/write
heads. As illustrated in FIG. 19A, the two-dimensional array of
channels or magnetic heads may be substantially aligned, such that
the pairs of channels or magnetic heads are aligned with the same
servo or data band in the down-track direction. Alternatively, as
illustrated in FIG. 19B, the two-dimensional array of channels or
magnetic heads may not be aligned in the down-track direction. It
is recognized that any suitable pattern of two-dimensional arrays
of channels or magnetic heads may be used and are within the spirit
and scope of the present disclosure. As described above, each of
the channels may be independently driven.
[0076] In one embodiment, a head in accordance with the various
embodiments of the present disclosure can be used for recording
magnetic transitions on magnetic media, for example, by supplying a
current through the coil conductor layer to create a magnetic field
in the magnetic layers. For example, a head in accordance with the
various embodiments of the present disclosure can be used to format
or verify magnetic media, e.g., write/read servo tracks to/from the
magnetic media. In other embodiments, as stated above, a head in
accordance with the various embodiments of the present disclosure
can be used to read/write data tracks. Additionally, as stated
above, each of the channels of a head in accordance with the
various embodiments of the present disclosure can be driven
simultaneously or independently. Independently driven channels
provide additional advantages to a head in accordance with the
various embodiments of the present disclosure, some of which are
described below, and others of which will be recognized by those
skilled in the art. Other embodiments of heads may include compound
systems of such heads, for example, with some heads being used as
servo verify heads and some heads being uses as pre-erase heads.
Further discussion on such compound heads may be found in U.S. Pat.
No. 7,283,317, issued Oct. 16, 2007, titled "Apparatus and Methods
for Pre-Erasing During Manufacture of Magnetic Tape," which is
hereby incorporated by reference herein in its entirety.
[0077] In further embodiments, a head in accordance with the
various embodiments of the present disclosure allows for complex
tape formatting techniques, such as un-staggered servo bands that
can linearly encode for the data band that lies in between each
pair of servo tracks. In a standard LTO format system, five bands
are staggered such that each pair of servo bands has a unique
stagger as compared to any other pair of servo bands. This format
is illustrated in FIG. 20, schematically shown in a view looking at
the head through the tape; a tape view would be the mirror image of
FIG. 20. As shown in FIG. 20, each data band 200 is bounded by a
pair of servo bands 202, each pair having a unique stagger. For
example, servo band 0 and servo band 1 have a lead/follow 1
stagger, servo band 1 and servo band 2 have a follow 1/lead
stagger, servo band 2 and servo band 3 have a lead/follow 2
stagger, and servo band 3 and servo band 4 have a follow 2/lead
stagger. The unique staggers are used to encode for the four data
bands 200 of the standard LTO format. A staggered servo technique
may be printed into the gap pattern during format head manufacture.
However, it is highly unlikely that for servo systems with a
greater number of servo bands, for example, 9, 13, or 17 servo
bands, that a physical stagger on the head proper will be a
suitable choice.
[0078] FIG. 21 illustrates two servo bands 210, 212 that lie on
either side of a data band 214. The number of data tracks within
the data band 214 will depend on how many positions the timing
based servo encodes and is a matter of design choice. Servo read
heads A and B 216 are positioned to read the servo tracks of servo
bands 212 and 210, respectively. This provides redundancy. Data
read/write heads may be positioned over the data band 214 region on
the same head slider system as servo reads A and B 216. Hence, the
position of the servo read heads A and B 216 provides the position
of the data read/write heads. In high speed systems, including
those developed in the future, there can be a large number of servo
bands as well as a relatively higher frequency content of the servo
signal as compared to currently available products. The
head-to-tape interface and spacing could become more critical, the
inductance for the head may need to be lower to write at higher
frequencies, the head efficiency may need to be greater, and the
moment density of the main film 152 that carries the gaps may need
to be higher.
[0079] As a result of the above factors, in one embodiment of the
present disclosure, it may be desirable to make a non-staggered
array of head elements for a given head bump line. It may further
be desirable, in accordance with one embodiment of the present
disclosure, regardless of the servo track or data band encoding
scheme, to address the servo head elements or channels
independently in order to encode the servo bands and thus, the data
band identifications. In the exemplary embodiment of FIG. 22, the
servo signals are repeated at a certain frequency in groups of
pulses, or frames 220, to average the ratios of the time-based
signals. According to the various embodiments of the present
disclosure, it is further possible to encode data in the servo
band. One such data encoding is illustrated in FIG. 22, wherein the
servo format band identification is encoded using the first and
fifth short pulse 224 of the pulse group 220 of servo band N+1 and
the second and fourth short pulses 226 of the pulse group 228 of
servo band N. As such, each servo band includes a unique servo band
identification encoded therein. These unique servo band
identifications can be further used to determine data band
identification. For example, as illustrated in FIG. 22, data band N
may be identified by being bound by servo band N having short
pulses 226 and servo band N+1 having short pulses 224. The encoding
illustrated in FIG. 22 is exemplary and is not limiting. One
advantage of having an equal lead and equal lag pulse in the same
frame is that the time base signal temporal signature will average
out the same as if no extra pulses were used at all. In this way,
data can be encoded without affecting, or substantially affecting,
the fundamental timing signature. Other ways of preserving the
timing based signature would be to use extra pulse codes after the
timing frame, with these extra pulses being ignored for timing
purposes and only attended to for other information, such as
manufactures information or servo and data band identification
information. Other methods of encoding servo band identification in
a unique manner may be used and are all within the spirit and scope
of the present disclosure, as the head allows for them all to be
used depending on the servo channel requirements and specific
designs. The more servo bands there are, the more complex the
encoding may be. In accordance with the present disclosure, using
independently addressable servo bands, encoding can be placed
electronically, and electronic encoding allows each head element to
be substantially physically identical to one another. While the
figures show static transition positions, it is entirely possible
to use frequency based servo band identification schemes, and such
frequency based servo band identification schemes are within the
spirit and scope of the present disclosure.
[0080] FIG. 23 illustrates a tape transport system 232 in
accordance with one embodiment of the present disclosure. The tape
transport system 232 may include a supply reel 234 and a take-up
reel 236. The tape transport system may further include tape guides
238 and/or other suitable tape guiding systems. A servo write head
240 can be positioned on the transport system 232, such that
magnetic media guided through the transport system 232 from the
supply reel 234 to the take-up reel 236 can be formatted, for
example, with the timing-based servo formats described above or
other suitable servo formats, including amplitude-based servo
formats. In further embodiments, a servo verify head 242, or read
head, may be positioned on the transport system 232 and can be used
to verify the magnetic transitions, and thus the servo formats,
written into the magnetic media by the servo write head 240. In
some embodiments, as disclosed above, the servo write head 240 and
servo verify head 242 may comprise a single compound head. It is
recognized that the various embodiments of a magnetic head in
accordance with the present disclosure may be suitable for data
read/write heads, and tape transport systems for such data
read/write heads may be similar to the transport system 232
illustrated in FIG. 23 and are within the spirit and scope of the
present disclosure.
[0081] Although the present invention has been described with
reference to preferred embodiments, persons skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention. For example,
each layer of the magnetic head may be made by one of a variety of
different manufacturing processes or techniques, including but not
limited to, deposition techniques, wet plating techniques, etching
techniques, etc. In some embodiments, planarization may be used
after any step, thereby, among other things, eliminating or
substantially eliminating height differential in the resulting tape
path and allowing for the application of an air skiving flat
contour. Other embodiments may include, for example, a complete
single coil turn that goes under and above the first magnetic
layer, multiple complete coil turns, each having a portion above
and below the first magnetic layer (which could make for a
particularly efficient inductive read head), and embedding
magneto-resistive read elements in each read channel for data read
or format verification. As stated previously, the magnetic head of
the present disclosure may be a single channel or multichannel
magnetic head. Furthermore, two-dimensional arrays of channels or
magnetic heads, including compound magnetic heads, including
writers and readers and erase heads and including data heads and
format head writers and readers are within the scope of the present
disclosure.
* * * * *