Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2001-06-11
2004-03-23
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
Reexamination Certificate
active
06710975
ABSTRACT:
BACKGROUND
The present invention relates to a process that reduces or compensates for stress between a slider and a supporter within a magnetic head assembly.
FIG. 4
illustrates a partial side view of a magnetic head within a hard disk drive. The magnetic head includes a slider
1
and a supporter
2
. The slider
1
is made of a ceramic material that includes a magnetic element
4
positioned near a trailing edge B. The magnetic element
4
includes an MR head (read head) and an inductive head (write head). The MR head detects a leakage magnetic field from a hard disk by detecting a magnetoresistive effect. The inductive head includes a coil. The supporter
2
includes a load beam
5
and a flexure
6
. The load beam
5
is made of a leaf springs material such as stainless steel and includes a hemispherical pivot
7
. The hemispherical pivot
7
projects downward from the flexure
6
and biases the slider
1
.
The flexure
6
is constructed of a thin leaf spring material such as stainless steel. The flexure
6
includes a fixed portion
6
a
and a tongue piece
6
b
. The slider
1
is fixed to the bottom surface of the tongue piece
6
b
by an adhesive layer
20
. The top surface of the tongue piece
6
b
is pressed against the pivot
7
. The slider
1
is attached to the bottom surface of the tongue piece
6
b
. Due to the elasticity of the tongue piece
6
b
, the slider
1
can change positions relative to the pivot
7
.
The slider
1
is pressed toward a disk D by the elastic force produced by the load beam
5
. The magnetic head is generally used in a hard disk drive of a contact start and stop (CSS) type. When the disk D is stationary, an ABS surface
1
a
of the slider
1
comes into contact with a recording surface of the disk D due to the elastic force generated by the load beam
5
. When the disk D rotates, air flows between the slider
1
and the surface of the disk D in a rotating direction of the disk D. Accordingly, the ABS surface
1
a
of the slider
1
is biased upward by the airflow, and the slider
1
is carried above the surface of the disk D at a height or a spacing of &dgr;1.
As shown in
FIG. 4
, the slider
1
inclines. This inclination allows the leading edge A to be positioned at a higher position than the trailing edge B relative to the disk D as the magnetic element
4
passes above the disk D. In this configuration, the MR head of the magnetic element
4
reads magnetic signals from the disk or the inductive head writes magnetic signals to the disk D.
As shown in
FIG. 5
, a gap separates the slider
1
from the tongue piece
6
b
of the flexure
6
. The distance h1 between the slider
1
and the tongue piece
6
b
receives the adhesive layer
20
. The adhesive layer
20
is made of a thermosetting resin. In an adhering process, the adhesive layer
20
is disposed between the slider
1
and the flexure
6
. UV curing is performed on the combination to temporarily fix the slider
1
to the flexure
6
. Heat treatment is then applied to cure the adhesive layer
20
, which affixes the slider
1
to the flexure
6
.
Since the slider
1
and the flexure
6
have different coefficients of thermal expansion, there can be problems affixing the slider
1
to the flexure
6
by a heat treatment. The slider
1
can deform as the slider
1
is secured to the tongue piece
6
b
. The amount of deformation that can occur is proportional to a difference between the coefficients of thermal expansion of the slider
1
and the flexure
6
, and is also proportional to a difference between the heat curing temperature and the room temperature.
In
FIG. 5
, the coefficient of thermal expansion of the flexure
6
is larger than that of the slider
1
. Thus, when the slider
1
deforms the ABS surface
1
a
warps outward. As the ABS surface
1
a
warps outward, the spacing h1 is reduced or lost which adversely affects the output of the magnetic element
4
as the disk D rotates.
In some conventional magnetic heads, the thickness of the adhesive layer
20
cannot be adjusted, and the distance h1 between the slider
1
and the flexure
6
is not large enough to adequately absorb the stress. When the distance h1 is small, the adhesive layer
20
cannot adequately absorb the stress, and the deformation of the slider
1
during the heat curing process of the adhesive layer
20
cannot be suppressed.
When the distance h1 is too large, it is difficult to position the slider
1
in a parallel position to the flexure
6
, and the slider
1
tends to be fixed in an inclined position. In such instances, the slider
1
cannot always be placed in a predetermined position. Thus, a spacing loss occurs and the slider
1
can collide with the surface of the disk D.
In addition, in some conventional magnetic head devices, the thickness of the adhesive layer
20
is not uniform, and the surface
20
a
of the adhesive layer
20
tends to undulate. In such instances, it is difficult to adequately secure the slider
1
to the flexure
6
through the adhesive layer
20
.
SUMMARY
Accordingly, presently preferred embodiments provide a magnetic head which is substantially free of the above-described problems. More specifically, the presently preferred embodiments provide a magnetic head in which an adhesive layer is disposed between the slider and the supporter. A gap or clearance of adequate size is maintained to reduce or compensate for the stress generated by different coefficients of thermal expansion of the slider and the supporter. In addition, the presently preferred embodiments provide a read and/or write apparatus having a magnetic head.
According to an aspect of the invention, a magnetic head includes a slider, a supporter, and an adhesive. The slider includes a magnetic element used for reading and/or writing. Preferably, the supporter has a different thermal expansion coefficient than the thermal expansion coefficient of the slider. An adhesive layer is disposed between the slider and the supporter. The adhesive layer includes particulate matter or components. The slider and the supporter are secured to each other by the adhesive layer. The particulate components preferably create a gap between the slider and the supporter. According to one presently preferred embodiment, the gap or clearance between the slider and the supporter is defined by the size of the particulate components within the adhesive.
Preferably, the adhesive layer disposed between the slider and the supporter can adequately absorb or transfer the stress induced by the different thermal expansion coefficients of the slider and the supporter. Thus, deformation of the slider during a heat curing process can be substantially reduced.
Since the particulate components are preferably mixed in the adhesive layer, an adhesive layer having uniform thickness can be used. Accordingly, a flat surface of the adhesive layer is easily created, and the slider is secured in a substantially parallel position to the supporter by the adhesive layer. Preferably, the size of the gap positioned between the slider and the supporter is within a range of about 20 to about 30 &mgr;m. When the gap is smaller than about 20 &mgr;m, the stress generated during the heat curing process by the thermal expansions of the slider and the supporter cannot always be adequately absorbed. When the gap is larger than about 30 &mgr;m, it can be difficult to secure the slider in a substantially parallel position to the supporter.
In addition, some of the particulate components preferably have a cross-sectional size of about 20 to about 30 &mgr;m in an area in which the slider and the supporter oppose each other. Accordingly, the height of the gap or distance between the slider and the supporter is preferably within the range of about 20 to about 30 &mgr;m. In addition, some of the particulate components having a cross-sectional height or thickness of about 20 to about 30 &mgr;m are preferably contained in the adhesive layer at about 5% weight to about 20% weight.
In addition, a Type D durometer hardness of the adhesive layer after heat curing is preferably withi
Sato Hidezi
Watanabe Mitsuru
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Klimowicz William
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