Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
1999-09-15
2002-02-26
Heinz, A. J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
Reexamination Certificate
active
06351351
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a suspension for supporting a magnetic head slider for use in a rigid magnetic recording disk drive (Hard Disk Drive: hereinafter abbreviated to as HDD).
2. Discussion of the Background
A wiring integrated suspension of the type that is integrally equipped with a part of a wiring structure connected to a magnetic head has recently come into use. The wiring structure is used for connection between the magnetic head and an integrated circuit (hereinafter abbreviated to as preamplifier IC) including a driver circuit for a write signal and a preamplifier circuit for a read signal. Where a magnetoresistive (MR) device is used for the magnetic head, it functions to read a signal, while an inductive device is used to write a signal. Accordingly, four or five wires (two or three wires for reading and two wires for writing) are required in this wiring structure.
FIG. 18
illustrates the wiring integrated suspension installed in the HDD, where the wiring integrated suspension
100
includes a wiring integrated flexure
110
with a magnetic head slider
200
mounted thereon, a load beam
120
for supporting the said flexure
110
and generating a force to press the magnetic head slider
200
against a magnetic disk
300
, and a base plate for securing the said load beam
120
to an arm
130
by caulking. In
FIG. 18
, the base plate is positioned under the arm
130
and therefore cannot be seen. The arm
130
can pivotally be moved around a pivot
140
on a plane in parallel with the magnetic disk
300
, so that the magnetic head slider
200
can be moved to a selected track position on the magnetic disk
300
. A voice coil motor (VCM)
150
is coupled to a proximal end portion of the said arm
130
so as to drive the arm
130
. A terminal (not illustrated) closer to a proximal end of the wiring structure integral with the suspension
100
is connected to a relay FPC (Flexible Printed Circuit)
160
closer to its distal end. The relay FPC
160
is, in turn, connected at its proximal end portion
162
to a print wiring board
170
such as an FPC, on which a preamplifier IC
171
is mounted.
FIG. 19
illustrates a wiring integrated suspension of the type that includes a flexure, a load beam and a base plate. In addition to this type of the wiring integrated suspension, there exists a wiring integrated suspension of the type that omits the base plate by directly welding a load beam to an arm.
Such wiring integrated suspensions have been proposed, for example, in Japanese Laid-Open (Kokai) Patent Publication Nos. 8-106617, 8-111015 (U.S. Pat. No. 5,657,186), 9-128728, U.S. Pat. No. 5,680,274, U.S. Pat. No. 5,717,547, etc.
FIGS. 19 and 20
respectively illustrate a perspective view of a wiring integrated suspension
100
of a conventional type, and an exploded perspective view of the wiring integrated suspension of FIG.
19
. In these figures, the upper side of the suspension faces the disk. As illustrated in
FIGS. 19 and 20
, the wiring integrated suspension
100
includes the wiring integrated flexure
110
, the load beam
120
and the base plate
180
, all of which are welded together at welds
99
.
The load beam
120
is provided with a load-bent portion
121
, thereby generating the force to press the slider against the magnetic disk.
The flexure
110
includes a wiring structure
111
(hereinafter referred to as flexure wiring structure) integrally formed thereon. The said flexure wiring structure
111
is provided at its proximal and distal ends with terminal pads
111
a
and
111
b
, each having a width being wider than a signal line portion
111
c
extending between the said ends. The terminal pad
111
b
closer to the FPC is used for connection to a wiring structure (hereinafter referred to as FPC wiring structure) of the relay FPC
160
, while the terminal pad
111
a
closer to the slider is used for connection to a terminal of the magnetic head. The terminal pad
111
b
closer to the FPC is positioned in parallel with the side of the arm
130
via a terminal bending portion
112
located closer to the proximal end of the flexure
110
. A magnetic-head-slider mounting region
113
is provided closer to the distal end of the flexure
110
so as to mount the magnetic head slider thereon. The flexure wiring structure
111
is usually connected to the relay FPC
160
with solder bumps, while the flexure wiring structure
111
is connected to a magnetic head terminal by Au ball bonding.
FIGS.
21
(
a
) and
21
(
b
) respectively illustrate vertical cross sections of the signal line portion
111
c
of the flexure wiring structure, and of the terminal pads
111
a
and
111
b
. As best illustrated in these figures, the wiring integrated suspension
110
includes a stainless-steel substrate
115
, a polyimide insulating layer
116
laminated on the disk-facing side of the said stainless-steel substrate
115
, a conductor layer
117
laminated on the disk-facing side of the said polyimide insulating layer and a polyimide protection layer
118
surrounding the said conductor layer
117
. At each of the terminal pads, the polyimide protection layer
118
is provided with an opening
118
a
, through which the conductor layer
117
is exposed to the outside.
As illustrated in
FIGS. 18
to
21
, the wiring integrated suspension of the conventional type includes the flexure wiring structure
111
that is connected to the FPC wiring structure via the terminal pad
111
b
closer to the FPC and the terminal pad
111
b
of the relay FPC. In consideration of an assembling error, the terminal pad
111
b
is usually of a rectangular shape with each side of approximately 0.4 to 0.5 mm.
The capacity of the terminal pads will be discussed hereinbelow. The wiring structure in the wiring integrated suspension employs pairs of wires, each pair including two wires. Accordingly, the capacity of the terminal pads does not represent a capacity Cps between one terminal pad and the stainless-steel substrate, but a capacity Cpad between two terminal pads corresponding to each pair of wires. The capacity directly existing between the two pads is much smaller than the capacity existing between the two pads via the stainless-steel substrate, so that the Cpad can be considered as being Cpad≈Cps/2. Where the terminal pads each are of the rectangular shape with each side of 0.4 to 0.5 mm as described above, providing the polyimide insulating layer
116
having a thickness of approximately 10 micrometers in this arrangement results only in the terminal pad capacity of approximately 0.4 to 0.6 pF.
Such a capacity in a joining region of the flexure wiring structure and the FPC wiring structure invites the following disadvantage. Specifically, the above terminal pad capacity results in mismatching of the impedance at the terminal pads, even if the characteristic impedance of the flexure wiring structure has been matched with that of the FPC wiring structure. This mismatching of the impedance in the wiring structure between the magnetic head and the preamplifier IC invites signal reflection in a mismatching portion, resulting in increase in rate of error occurrence in reading data from and writing data to the magnetic disk by the head. The data transferring speed has recently become higher than ever, so that the signal reflection in the wiring structure poses a serious problem in data transfer at such a high speed (see K. B. Klaassen et al, “High Speed Magnetic Recording”, IEEE TRANSACTIONS ON MAGNETICS Vol. 34, No. 4, pp. 1822-1827, 1998).
Specifically, a high-speed data transfer causes a large number of high frequency elements in signals. The mismatching of the impedance at the terminal pads results from the above-described capacity Cpad. The impedance 1/wCpad resulting from the said terminal pad capacity is decreased as the frequency is increased, in which w is an angular frequency 2&pgr;f.
When Zc<<1/wCpad, in which Zc represents the characteristic impedance of the wiring structure, the mismatching of the impedance at the ter
Castro Angel
Heinz A. J.
Jordan and Hamburg LLP
Suncall Corporation
LandOfFree
Magnetic head suspension does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic head suspension, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic head suspension will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2940436