Note: Descriptions are shown in the official language in which they were submitted.
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INTEGRATED MAGNETIC HEAD SLIDER ASSEMBLY
DESCRIPTION
Technical Field
This invention relates to integrated thin film
magnetic head slider assemblies and to a method of
batch fabrication of integrated thin film magnetic head
slider assemblies.
An object of this invention is to provide an
improved means and method of making integrated thin
film magnetic head air bearing slider assemblies.
Another object of this invention is to provide a
method for batch fabrication of identical thin film air
bearing head slider assemblies, having high performance
at very low cost.
Another object is to provide a thin film magnetic
head slider assembly having protected thin film layers
with ready access to electrical contacts.
~ackground Art
Thin film magnetic heads have been proposed for
use in data processing apparatus, such as magnetic disk
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files, to enable higher density recording and readout.
Prior art disk files have employed laminated or ferrite
heads mounted to air bearing head sliders, which allow the
heads to fly close to the surface of a rotating magnetic
disk, thereby affording increased data density. In prior
art devices, thin film heads are bonded to air bearing
sliders by epoxy, for example. Such design encounters
problems in control of the thickness of the final assembly,
and in structural stability, among other things. The epoxy
bond tends to yield and flow under stress, which would cause
relative displacement of the slider parts. Also, in the
process of assembling the thin film transducer and the sub-
strate, it is difficult to determine when lapping has been
completed sufficiently to provide the desired throat height.
These problems become more serious when both write and read
thin film elements need to be aligned, and to be machined to
the same throat height. In addition, during the bonding o
the elements under high temperature, the Permalloy material
used for thin film heads tend to re-crystallize, which
results in degradation of the permeability of the thin
films.
CROSS-REFERENCE TO RELATED PATENT
In U.S. Patent 4,130,847 issued December 19, 1978, to
N.L. Head et al and assigned to the same assignee, an
assembly of an air bearing slider element and a -thin film
~5 transducer is disclosed but not claimed.
In U.S. Patent 4,219,853 issued August 26, 1980, a pro-
cess for depositing thin film magnetic transducers on a non-
magnetic ceramic substrate is described.
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1 SUMMARy OF THE INVENTION
The invention provides an integrated thin film magnetic
head slider assembly comprising:
a thin film head assembly having first and second thin
film magnetic pole pieces;
a nonmagnetic substrate forming a slider for supporting
said thin film head assembly;
said first magnetic pole piece being deposited directly
onto said substrate; and
a layer forming a transducing gap disposed between said
pole pieces.
Another aspect of the invention provides a magnetic
head assembly including an air bearing slider, and a thin
film transducer which is disposed along the back surface at
the trailing end of the slider. The effective transducing
gap of the thin film transducer is l~cated at the air
bearing surface of the slider. The air bearing surface is
substantially perpendicular to the back surface. In a
preferred embodiment, the air bearing slider has longitu-
dinal rails with taper-flat portions, as described in U.S.
Patent 3,855,625.
By virtue of the configuration of the instant inven-
tion, it is possible to batch fabricate a multiplicity of
like thin film magnetic head assemblies by direct deposition
of thin film layers forming magnetic transducers on one
surface of a substrate block. The thickness of the block is
made to be substantially the desired length of the air
bearing slider. After deposition of the thin film trans-
ducers, which are uniformly spaced in rows and columns, the
substrate block is saw cut into rows. Air bearing rails and
taper-flat portions are then formed for each transducer in a
row. Subsequently, each finished row is cut so that
individual sliders, each having a deposited thin film
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1 assembly, are separated into completed integrated magnetic
head slider assemblies.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in detail with
reference to the drawing in which:
FIGURE 1 is an isometric view depicting a substrate
block with deposited thin film transducers and
electrical contacts, in accordance with this invention;
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FIGURE 2 is an enlarged isometric view of an
individual thin film head slider assembly, taken from
the back surface and trailing end of the air bearing
slider;
FIGURE 3 is a side plan view of the air bearing
slider;
FIGURE 4 is a bottom plan view of the air bearing
slider; and
FIGURE 5 is a side view of a thin film transducer
deposited on the substrate, shown partially broken
away.
DISCLOSURE OF THE INVENTION
As depicted in FIG. 1, a multiplicity of thin film
head structures 10 are simultaneously deposited di-
rectly on a major surface 11 of a substrate block 1~.The thin film head structures 10 are deposited and
uniformly spaced on the block in rows and columns~ The
substrate block is made of a nonmagnetic ceramic ma-
terial such as alumina, and is shaped and polished to a
smooth finish prior to the deposition of the thin film
head structures. The substrate block is finished to a
uniform thickness T, which when added to the thickness
of a thin film head structure deposited on the sub-
strate, equals the desired length of the air bearing
~5 slider 14, made in accordance with this invention.
/a
After the thin film head structures ~ have been
directly deposited on the substrate block, the block is
saw cut into smaller sections 1~, each section having a
row of thin film head assemblies~
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At this point air bearing slider rails 18 and taper-
flat portions 20 are shaped, as illustrated in FIG. 2, by
cutting or etching a bottom surface 22 (See FIG. 4) of the
slider assembly. The bottom surface 22 is perpendicular -to
the major surface 11 on which the head structures 10 are
deposited. After the sections 16 have been suitably shaped,
with formed air bearing rails 18 and taper-flat portions 20
for each thin film head structure, the sections are saw cut
into separate air bearing magnetic head sliders 14. Prior
to each saw cut procedure, the substrate surface is scribed
through the thickness of an overcoat alumina layer to iso-
late the alumina from effects of the saw cuts to preserve
integrity of the alumina overcoat during the slicing process.
In keeping with this invention, batch fabrication of
the thin film head structures 10 is achieved both by de-
position of thin film layers throughout photoresist masks,
as well as by deposition of blanket layers followed by
photolithography and etching techniques so that each head
structure 10 is developed concomitantly on the common sub-
strate 12. To this end, the basic process, which is dis-
closed in U.S. Patent 4,219,853 is utilized.
To implement the process of thin film head construc-
tion, the nonmagnetic ceramic substrate 12 is prepared by
polishing the surface of the substrate to a very fine finish.
The substrate is cleaned and prepared for the deposition of
a first pole piece layer 24, made of Permalloy, illustrated
in FIG. 5.
Prior to plating the first Permalloy pole piece layerl
the ceramic substrate is made conductive to accommodate the
plating material. A conductive layer
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is formed by metallizing the major surface 11 of the
substrate with a very thin Permalloy film, in the range
of 50 to lO0 nanometers, which may be deposited by
either vacuum evaporation or sputtering. The first
pole piece Permalloy layer is then plated onto the
conductive surface to a thickness of 1 to 3 micrometers
through a photoresist mask, having a predetermined
pattern.
After plating the first magnetic pole piece layer
24, the thin metallized conductive Permalloy film is
removed by sputter etching.
At this point, a thin nonmagnetic layer 26, which
will serve as the transducing gap of the magnetic head,
is deposited onto the surface of the first pole piece,
by sputtering alumina to a desired thickness which will
delineate the length of the transducing gap.
Using an appropriate photoresist mask and a 50%
phosphoric acid solution, the alumina is then etched
off from the back gap closure area 28 of the first Per-
malloy layer pole piece 24. The back gap closure 28 isthe area at which the two Permalloy pole pieces 24 and
30 are in contact to close the magnetic circuit.
The first pole piece Permalloy layer 24 is covered
with photoresist, which is patterned to form a pad of
photoresist insulation 32 where the Permalloy is to be
subsequently crossed by a copper coil conductor 34.
The photoresist is then baked in a vacuum oven.
The copper coil 34 and conductive leads 36 (see
FIG. l) are electroplated over the insulation 32, after
a conductive film of copper has been deposited by
metallization using vacuum evaporation or sputtering.
The copper film, having a thickness in the range of 5Q
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lO0 nanometers, adheres to a thin film of chromium, of
about 5 nanometers, which has been first deposited.
The copper coil 34 which is about 2-4 micrometers thick
is plated through a photoresist mask onto the con-
ductive copper film. After plating the relativelythick copper coil 3'1, the thin film of copper with
chromium undercoat is removed in unwanted areas by
sputter etching.
A photoresist mask pattern is formed and baked in
a vacuum oven to provide a leveling pad of insulation
in the region where the copper coil 34 will be crossed
by the second pole piece Permalloy layer 30. The
second pole piece Permalloy layer is then plated over
the insulation layer 32, in the same manner as the
deposition of the first Permalloy layer 24. This
second pole piece 30 makes contact with the first pole
piece 24 in the back gap area 28 and completes the yoke
structure necessary for realizing a closed magnetic
circuit with a nonmagnetic transducing gap.
Next, electrical contacts (not shown) are formed
on the insulator by plating through a photoresist mask.
The electrical contacts are formed as copper studs of
about 25 to 50 micrometer thickness, and are connected
by the conductive leads 36 to the coil structure 34.
To protect the thin film structures lO, an over-
coat insulating layer 38 of A12O3 of about 25-50 micro-
meter thickness is deposited over the exposed second
pole piece 30. The copper contact studs are then
exposed by lapping.
After the deposition of the multiplicity of thin
film structures lO and conductor leads 36, the sub-
strate block ll is separated into row sections 16, and
machined to form air bearing configurations, and then
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divided into individual head sliders 14. The head
slider assemblies fabricated by the batch process
described herein are substantially uniform in dimen-
sions and material characteristics. The structural
stability of the slider assembly is enhanced because
the thin film structure is directly deposited onto the
slider substrate, and no epoxy or adhesive is used for
bonding. The thickness of the substrate block is
determinative of the desired length of the air bearing
slider, thereby saving lapping and machining steps. By
virtue of the slider design, the air bearing rails and
taper-flat sections may be formed, by etching for
example, in one procedural step for several sliders
joined in a row section.
It should be understood that the scope o this in-
vention is not necessarily limited to the dimensions,
materials and parameters described above.
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