Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2002-03-15
2004-08-10
Chen, Tianjie (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
Reexamination Certificate
active
06775101
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to floating type magnetic head devices provided for hard disk apparatuses or the like. In particular, the present invention relates to a magnetic head having a slider, and a flexure which supports the slider and which is electrically connected thereto with a conductive resin film.
2. Description of the Related Art
FIG. 4
is a partial side view showing the structure of a conventional magnetic head device for a hard disk apparatus. This magnetic head device is composed of a slider
1
, and a supporting member
2
which supports the slider
1
.
The slider
1
is formed of a ceramic material or the like. A thin-film element
4
is provided on a trailing end B of the slider
1
. The thin-film element
4
includes an MR head (reading head) for reading magnetic signals by detecting a leakage magnetic field, using a magnetoresistance effect, from a recording medium such as a hard disk, and an inductive head (writing head) comprising a coil is formed by patterning.
The supporting member
2
is composed of a load beam
5
and a flexure
6
. The load beam
5
is formed of a leaf spring material such as stainless steel, and has a bent section
5
a
on each side of the front portion thereof so as to have rigidity. A predetermined resilient force can be obtained at the base end of the load beam
5
where the bent section
5
a
is not formed.
A spherical pivot
7
(which protrudes downward in the figure) is formed in the vicinity of the front portion of the load beam
5
, and the slider
1
abuts against the pivot
7
with the flexure
6
provided therebetween. The flexure
6
is formed of a leaf spring such as stainless steel. The flexure
6
includes a fixed section
6
a
and a tongue
6
. A step
6
c
connects the fixed section
6
a
to the tongue
6
b.
As shown in
FIG. 4
, the slider
1
is bonded to the lower surface of the tongue
6
b
with a resin adhesive
20
. This resin adhesive
20
is formed of, for example, a thermosetting epoxy resin adhesive. A conductive pattern (not shown in the figure) is provided on the rear side of the tongue
6
b
. In addition, an electrode terminal section (not shown in the figure), formed of a thin film extending from the thin-film element
4
, is provided on the trailing end B of the slider
1
. At the junction between this conductive pattern and the electrode terminal section, a joint
9
is formed by ball bonding using gold (Au) or the like. Furthermore, the joint
9
is covered with a reinforcing resin film
10
, which provides protection for the joint
9
.
A fillet-shaped conductive resin film
21
is formed between the leading end A of the slider
1
and the tongue
6
b
. This conductive resin film
21
is provided to secure the electrical connection between the slider
1
and the flexure
6
, and to dissipate static electricity in the slider
1
to the supporting member
2
side.
The upper surface of the tongue
6
b
abuts against the pivot
7
provided on the load beam
5
. This permits the slider
1
bonded to the lower surface of the tongue
6
b
to freely change attitude, by means of the resilience of the tongue
6
b
, with the apex of the pivot
7
serving as a fulcrum.
This conventional magnetic head device is used for a so-called “CSS” (Contact Start Stop) type hard disk apparatus or the like, and when the disk D stops, an air bearing surface (i.e., a floating surface, hereinafter referred to as an ABS)
1
a
of the slider
1
is brought into contact with a recording surface of the disk D. The slider
1
of the magnetic head device is urged toward a disk D by the resilient force of the base end of the load beam
5
. When the disk D starts, an airflow occurs between the slider
1
and the surface of the disk D in the direction of the disk movement, and the slider
1
is lifted above the surface of the disk D by a short distance &dgr;
2
(spacing) because of the lifting force caused by the airflow.
While the slider
1
is lifted (as shown in FIG.
4
), the leading end A of the slider
1
is lifted higher above the disk D than the trailing end B. While maintaining this lifting attitude, magnetic signals are either detected from the disk by the MR head of the thin-film element
4
, or are written on the disk by the inductive head.
A process for manufacturing the magnetic head device described above generally comprises the steps of bonding the upper surface of the slider
1
to the lower surface of the tongue
6
b
of the flexure
6
with the resin adhesive
20
, electrically connecting an electrode of the flexure
6
to a pad portion of the slider
1
with the joint
9
(such as a gold ball), and inspecting the electrical characteristics of the magnetic head device.
In the step of inspecting the electrical characteristics described above, the inspection is performed under conditions almost identical to actual usage conditions. That is, for example, the ABS (floating surface)
1
a
of the slider
1
is in contact with the recording surface of the disk D, the disk D is then started, and subsequently, the slider
1
is lifted above the surface of the disk D by a short distance &dgr;
2
(spacing). As a result, the slider
1
may be electrified by friction with the disk D or the like, and a potential difference between the slider
1
and the disk D may be generated.
This problem may also occur in other types of magnetic head devices. For example, in a load/unload type head, a recording medium and the slider are theoretically not brought into contact with each other. However, they are brought into contact with each other under certain conditions (e.g., contacts can occur while the disk rotates), and as a result, a potential difference between the slider and the recording medium may be generated as in the case of the CSS type device.
In the magnetic head described above, it has been generally believed that electrical conduction in the conductive resin film
21
is ensured by dielectric breakdown which occurs between particles of the conductive filler compounded with the resin. Accordingly, the electrical conduction cannot be obtained if a voltage greater than a predetermined threshold value is not applied. That is, electrical conduction between the slider
1
and the flexure
6
cannot be ensured until the voltage applied thereto exceeds the predetermined threshold value.
Consequently, when the threshold value is larger than an electrostatic breakdown voltage in which electrostatic damage to an MR element or the like occurs, electrical conduction between the slider
1
and the flexure
6
cannot be ensured, and when the slider
1
is electrified, the charges therein cannot be dissipated to the supporting member
2
side via the conductive resin film
21
. As a result, there has been a problem in that electrostatic breakdown of a thin-film element
4
(such as an MR head) may occur when this electrified slider
1
is brought into contact with metal or the like.
In addition, as shown in
FIG. 4
, the trailing end B of the slider
1
is rigidly bonded to the tongue
6
b
of the flexure
6
by the joint
9
formed by ball bonding. Furthermore, as shown in
FIG. 4
, the conductive resin film
21
is provided between the leading end A of the slider
1
and the tongue
6
b
of the flexure
6
.
However, in conventional magnetic head devices, the flatness of the ABS (floating surface)
1
a
of the slider
1
can easily vary. In other words, the crown height (which will be described later) easily varies, and hence, it has been very difficult to maintain a constant spacing &dgr;
2
. The reason the flatness of the ABS
1
a
of the slider
1
(i.e., the crown height) can easily vary is thought to be because the conventional conductive resin film
21
provided between the slider
1
and the lower surface of the tongue
6
a
of the flexure
6
contains a rigid resin such as a thermosetting epoxy resin as an adhesive (binder).
In addition, since the slider
1
has a coefficient of thermal expansion different from that of the flexure
6
, when the conductive resin film
21
provi
Kimura Takashi
Satoh Hidezi
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Chen Tianjie
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