Magnetic head

Details Magnetic head Magnetic head

1999-02-08

2001-10-23

Cao, Allen (Department: 2652)

Dynamic magnetic information storage or retrieval

Fluid bearing head support

Disk record

C360S235100

Reexamination Certificate

active

06307714

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a floating type magnetic head device for use in a hard disk apparatus or the like. In particular, the invention relates to a magnetic head in which a slider and a flexure for supporting the slider are bonded together with an adhesive.
2. Description of the Related Art
FIG. 3
is a partial side view of a known magnetic head device for use in a hard disk apparatus.
The magnetic head device includes a slider
1
and a support
2
for supporting the slider
1
.
The slider
1
is composed of a ceramic material or the like. A thin-film element
4
is provided on the trailing end B, and the thin-film element
4
includes an MR head (read head) for reading magnetic signals by detecting a leakage magnetic field from a recording medium such as a hard disk, using a magnetoresistance effect, and an inductive head (write head) in which a coil and so on are formed by patterning.
The support
2
includes a load beam
5
and a flexure
6
.
The load beam
5
is composed of a leaf spring material such as stainless steel, and has a bent section
5
a
having rigidity on each side of the front portion. A predetermined elastic force can be displayed at the base end of the load beam
5
in which the bent section
5
a
is not formed.
A spherical pivot
7
which protrudes downward in the drawing is formed in the front portion of the load beam
5
, and the slider
1
abuts against the pivot
7
with the flexure
6
therebetween.
The flexure
6
is composed of a leaf spring such as stainless steel. The flexure
6
includes a fixed section
6
a
and a tongue
6
b
, and a step
6
c
connects the fixed section
6
a
to the tongue
6
b.
As shown in
FIG. 3
, to the lower surface of the tongue
6
b
, the slider
1
is bonded with a resin adhesive
20
. An example of the resin adhesive
20
is a thermosetting epoxy resin adhesive.
A conductive pattern (not shown in the drawing) is provided on the reverse side of the tongue
6
b
, and an electrode terminal section (not shown in the drawing) formed of a thin film extracted from the thin-film element
4
is provided on the trailing end B of the slider
1
. At the junction between the conductive pattern and the electrode terminal section, a joint
9
is formed by ball bonding using gold (Au) or the like. The joint
9
is covered with a reinforcing resin film
10
for protection.
A fillet conductive resin film
21
is formed between the leading end A of the slider
1
and the tongue
6
b
. The conductive resin film
21
is provided to secure electrical connection between the slider
1
and the flexure
6
and to dissipate static electricity to the support
2
.
The upper surface of the tongue
6
b
abuts against the pivot
7
formed on the load beam
5
, and the slider
1
bonded to the lower surface of the tongue
6
b
can change the attitude freely, by means of elasticity of the tongue
6
b
, with the apex of the pivot
7
serving as a fulcrum.
The slider
1
of the magnetic head device is applied force with the elastic force of the base end of the load beam
5
in the direction of the disk D. The 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 (flying surface)
1
a
comes into contact with the recording surface of the disk D. When the disk D starts, an airflow occurs between the slider
1
and the surface of the disk D along the disk movement, and the slider
1
is lifted by a short spacing &dgr;
2
from the surface of the disk D because of a lifting force caused by the airflow.
When the slider
1
is lifted, as shown in
FIG. 3
, the leading end A of the slider
1
is lifted higher above the disk D than the trailing end B. While maintaining the lifting attitude, magnetic signals from the disk are detected by the MR head of the thin-film element
4
, or the magnetic signals are written by the inductive head.
In the conventional magnetic head device, however, the flatness or crown height of the air bearing surface
1
a
of the slider
1
may easily change, resulting in extreme difficulty in setting the spacing &dgr;
2
at a given amount.
The flatness or crown height of the air bearing surface
1
a
of the slider
1
easily changes because a rigid adhesive such as a thermosetting epoxy resin adhesive is conventionally used as the resin adhesive
20
for bonding the upper surface of the slider
1
and the lower surface of the tongue
6
b
of the flexure
6
together.
As shown in
FIG. 3
, 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.
Additionally, since the slider
1
has a coefficient of thermal expansion which is different from that of the flexure
6
, if the resin adhesive
20
bonding the upper surface of the slider
1
and the lower surface of the tongue
6
b
together is rigid, thermal stress owing to the difference in coefficient of thermal expansion between the tongue
6
and the slider
1
may affect the slider
1
with the resin adhesive
20
therebetween, resulting in adhesive deformation with respect to the slider
1
.
Generally, since the flexure
6
has a larger coefficient of thermal expansion in comparison with the slider
1
, for example, in the low temperature region, the air bearing surface
1
a
of the slider
1
is deformed to be convex in relation to the disk D, and thus a spacing loss increases, resulting in a decrease in output.
In the high temperature region, the air bearing surface
1
a
of the slider
1
is deformed to be concave in relation to the disk D, and thus it is highly possible that the trailing end B of the slider
1
collides with the surface of the disk D, and the minimum flying height (spacing amount) cannot be guaranteed.
Also, as shown in
FIG. 3
, when 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
, if the conductive resin film
21
is rigid the same as the resin adhesive
20
, both the trailing end B and the leading end A of the slider
1
are rigidly bonded, resulting in larger adhesive deformation with respect to the slider
1
owing to thermal stress.
SUMMARY OF THE INVENTION
The present invention has been achieved in order to overcome the difficulties noted above with respect to the conventional art. It is an object of the present invention to provide a magnetic head which can reduce adhesive deformation with respect to a slider by using a resin adhesive which is flexible particularly after curing in order to bond the slider and a flexure together.
In accordance with the present invention, a magnetic head includes a slider having an element for recording and/or reproducing and a flexure having an elastically deformative tongue. The slider and the flexure are bonded together with a resin adhesive therebetween. The resin adhesive has a Young's modulus E in the range of 700 to 5,200 kg/cm
2
at 25° C. and a bond strength of 50 gf or more.
Preferably, the resin adhesive has a glass transition temperature in the range of 4 to 70° C.
Also, preferably, the resin adhesive has a product {E·(Tg−25° C.)} obtained by multiplying the Young's modulus E at 25° C. by the temperature obtained by subtracting 25° C. from the glass transition temperature Tg in the range of 7,000 to 234,000 kg·° C./cm
2
.
Also, when a conductive resin film is formed between an end of the slider and the flexure as a countermeasure against static electricity, the conductive resin film used has the same properties as those of the resin adhesive described above.
Although, in conventional art, wiring is directly connected to a slider in order to output signals from a thin-film element provided on the slider or to input signals to the thin-film element, as the slider is miniaturized, use of a magnetic head, in which a conductive pattern is formed on a flexure for bonding the slider and the conductive pattern and a conductive terminal section provided on the slider are bond

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