Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
2001-01-31
2003-02-18
Cao, Allen (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
Reexamination Certificate
active
06522504
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to disk drives. More particularly, the present invention relates to head stack assemblies and disk drives using a reversed direction head gimbal assembly.
2. Description of the Prior Art
A typical hard disk drive includes a head disk assembly (“HDA”) and a printed circuit board assembly (“PCBA”). The HDA includes at least one magnetic disk (“disk”), a spindle motor for rotating the disk, and a head stack assembly (“HSA”); that includes a read/write head with at least one transducer for reading and writing data. The HSA is controllably positioned by a servo system in order to read or write information from or to particular tracks on the disk. The typical HSA has three primary portions: (1) an actuator assembly that moves in response to the servo control system; (2) a head gimbal assembly (“HGA”) that extends from the actuator assembly and biases the head toward the disk; and (3) a flex cable assembly that provides an electrical interconnect with minimal constraint on movement.
A “rotary” or “swing-type” actuator assembly comprises a body portion that rotates on a pivot bearing cartridge about a pivot axis between limited positions, a coil portion that extends from one side of the body portion to interact with one or more permanent magnets to form a voice coil motor, and an actuator arm that extends from an opposite side of the body portion to support the HGA.
A typical HGA includes a load beam, a gimbal attached to an end of the load beam, and a head attached to the gimbal. The load beam has a spring function that provides a “gram load” biasing force and a hinge function that permits the head to follow the surface contour of the spinning disk. The load beam has an actuator end that connects to the actuator arm and a gimbal end that connects to the gimbal that carries the head and transmits the gram load biasing force to the head to “load” the head against the disk. A rapidly spinning disk develops a laminar airflow above its surface that lifts the head away from the disk in opposition to the gram load biasing force. The head is said to be “flying” over the disk when in this state.
As shown in
FIG. 1
, some early HGAs
100
included a number of wires
102
within a tube
104
attached to a side of the actuator arm (not shown in FIG.
1
). Herein, the terms “proximal” and “distal” refer to the relative positions of a structure with respect to the pivot axis. For example, the proximal end of a structure is closer to the pivot axis of the actuator arm than is the same structure's distal end. Consistent with the foregoing, the proximal end of each of the wires
102
emerging from the proximal end of the tube is typically soldered to the flex cable. The distal end of each of the wires
102
emerging from the, distal end of the tube
104
may be attached to a corresponding conductive pad of the transducer
106
attached to the trailing edge
108
of the head
110
(the edge of the head
110
that trails as the disk
112
rotates, under the head
110
in the direction indicated by arrow
114
). In turn, the head
110
is attached to the gimbal
116
that is supported by the load beam
118
. In this configuration, the wires
102
are typically unsupported as they loop from the distal end of the tube to the conductive pads on the transducer
106
.
This configuration was adequate for early HGAs. However, more recent developments in the disk drive industry, such as the continuing miniaturization of slider assemblies (including the. head and the transducer) and the transition to magnetoresisitive (MR) heads have led to abandoning such looping wire configurations in favor of a configuration wherein conductive traces are laid on a polyimide film formed on the gimbal assembly. Such technologies are variously named TSA (Trace Suspension Assembly), NSL (No Service Loop), FOS (Flex On Suspension) and the like. Whatever their differences, each of these technologies replaces the discrete twisted wires
102
shown in
FIG. 1
with conductive traces (copper, for example) on a layer of insulating material (such as polyimide, for example). These conductive traces interconnect the transducer elements of the head to the drive preamp and the circuits associated therewith.
A conventional TSA-type HGA
200
is shown in
FIGS. 2 and 3
. As shown therein, a layer of conductive material is deposited or otherwise formed onto a layer of polyimide on the gimbal
216
and selectively etched to create the conductive traces
222
and the polyimide layer(s)
220
. A weld
224
electrically connects the transducer
206
to the conductive traces
222
. As in the HGA
100
depicted in
FIG. 1
, the transducer
206
is attached to the trailing edge
208
of the head
210
. The conductive traces
222
, as best seen in
FIG. 2
, are coupled to the trailing edge of the head
210
and are routed back in the proximal direction toward the HGA's flex circuit and preamp (not shown in
FIG. 1
, see
FIG. 9
) via a lateral extensions of the gimbal
216
called outriggers, as shown at reference numeral
226
. However, the outriggers
226
negatively impact the inertia and stroke of the HGA
200
, and degrade the performance of the drive in which the HGA
200
is deployed.
In an effort to reduce the HGA's inertia and stroke, FOS-type designs similar to that shown in
FIGS. 4 and 5
have been proposed. As shown therein, the HGA
400
includes conductive traces
422
formed on a polyimide layer
420
that are routed under the head
410
and back toward the flex circuit and preamp without using outriggers on either side of the head
410
. This reduces the size of the gimbal
416
and correspondingly reduces the HGA's inertia and stroke, but disadvantageously increases the separation between the load point
426
(load point between the load beam
418
and the gimbal
416
) and the center of gravity
428
of the head
410
.
What are needed, therefore, are improved HGAs, HSAS. In particular, what are needed are improved disk drives, HGAs and HSAs that have reduced inertia and stroke, that do not use discrete wires or outriggers and that do not exhibit an unacceptable vertical separation between the HGA load point and the center of gravity of the head.
SUMMARY OF THE INVENTION
Accordingly, this invention may be regarded as a head stack assembly for a disk drive Shaving a disk. According to the present invention, the head stack assembly comprises a body portion including a bore defining a pivot axis; an actuator arm cantilevered from the body portion and a head gimbal assembly supported at the actuator arm. The head gimbal assembly includes a load beam, which includes a first load beam surface facing toward the disk and a second load beam surface facing away from the disk. A plurality of conductors are at least partially supported by the first load beam surface. Each conductor includes a proximal conductive pad, a distal conductive pad and a conductive path between the proximal and distal conductive pads, the proximal conductive pad being closer to the pivot axis than the distal conductive pad. A gimbal is coupled to the load beam, the gimbal including a gimbal proximal end that supports the respective distal conductive pads and a gimbal distal end. A head is attached to the gimbal, the head including a head proximal end and a head distal end. The head distal end is closer to the gimbal distal end than the gimbal proximal end and the head proximal end is disposed adjacent the respective distal conductive pads. A plurality of head conductive pads are coupled to the head proximal end. The head gimbal assembly also includes means for electrically connecting each of the plurality of head conductive pads to a corresponding distal conductive pad.
According to further embodiments, the plurality of conductors may include an array of conductive traces. The array of conductive traces may define a plane substantially parallel to the pivot axis. The connecting means may include solder or gold bond bonding, for example. The head may include a transd
Cao Allen
Kim Esq. W. Chris
Shara, Esq. Milad G.
Western Digital Technologies Inc.
Young Law Firm
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