Composite type magnetic head using composite metallic wire

Details Composite type magnetic head using composite metallic wire Composite type magnetic head using composite metallic wire

2000-04-12

2001-01-30

Kincaid, Kristine (Department: 2831)

Electricity: conductors and insulators

Conduits, cables or conductors

Conductor structure

C428S379000

Reexamination Certificate

active

06180890

ABSTRACT:

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a composite metallic wire which can be suitably used as a coil wire for a composite type magnetic head, particularly, as a coil wire for a high-density magnetic recording head and to a magnetic head using the composite metal wire.
With the spread of computers, an increase of a capacity and a speed up of a magnetic recording apparatus have been rapidly improving. Accordingly, a magnetic head is required to have (1) a smaller size and (2) a lower inductance.
In order to enlarge a valid recording area and improve a running followability of a magnetic recording apparatus, a slider is changed from one having dimensions of 4.3 mm×2.9 mm×0.86 mm, which was a standard slider originally, to another one having dimensions of 2.0 mm×1.6 mm×0.46 mm, which is a main current slider and called “50% slider”. Further, a slider called “30% slider” is under investigation.
In order to improve a transmitting speed, it is required that a frequency upon reproducing a record. Therefore, it is required that an inductance of a magnetic head is lowered so as to shorten a rise time of a recording current in a range of high frequencies. For example, in the case of 600 Mb/in
2
, the inductance is required to be 0.9 &mgr;H or less. In the case of 700 Mb/in
2
, the inductance is required to be 0.7 &mgr;H or less. For reducing an inductance of a magnetic head, it is required that a cross sectional area of a magnetic path is reduced, for example, a thickness of a magnetic core is reduced, thereby causing a problem of reducing an efficiency of the head. To solve the problem, a magnetic path should be shortened. Specifically, a window for a coil should be made smaller, thereby reducing an inductance.
However, a window for a coil of a magnetic core is required to be wound by a coil wire with a predetermined number of turns. For example, in the case of 600 Mb/in
2
, the number is 26, and in the case of 700 Mb/in
2
, the number is 24. Therefore, the window is required to have a size sufficient for the winding. Accordingly, a minimum size of the window for a coil depends on a diameter of a wire used for the coil.
FIG. 3
shows a core chip in which a conventional wire is used. The core chip
10
mainly consisting of a trailing core
16
and leading core
18
. A coil
28
made of a wire is wound around a window
12
for a coil formed by the trailing core
16
and a leading core
18
.
The surfaces of the trailing core
16
and the leading core
18
which are facing to each other are covered with metallic films
22
, respectively. Between these films, a magnetic gap
20
consisting of a glass
24
is formed. Incidentally,
26
is an insulating protective tube.
As shown in
FIG. 3
, a conventional core chip in which a wire is used, the coil has a large diameter. Accordingly, the window
12
for a coil could not be made smaller, and inductance could not be reduced.
Conventionally, an alloy of copper and silver has been used as a material for the wire having a minimum diameter of 22 &mgr;m and a maximum tensile strength of 20 g.
It is technically possible to thin down a copper alloy wire conventionally used. However, indeed, a wiring operation is manual, and therefore, a wire having a low tensile strength has problems of the snapping of the wire, and the like. Accordingly, the wire is required to have a tensile strength of at least 20 g. Therefore, it is difficult to use a thin copper alloy wire as a coil wire from the view point of mass-production.
Accordingly, it is difficult to achieve a memory density of 600 Mb/in
2
or more by using a magnetic head using a wire such as a conventional copper alloy wire.
As a structure of a composite type magnetic head, a core chip embedding type is known.
For producing this magnetic head, a track machining is first given, a core chip having a thickness (d) of 50 &mgr;m is inserted into a groove for inserting a core chip and tentatively fixed. Then, glass is fused and poured in the periphery of the track portion so as to fix the core chip to the slider. After that a tentative fixing member in a back portion is removed, and a resin is poured into the portion to fix the core chip to the slider. Then, surplus glass on a sliding surface is removed, and simultaneously, the surface is polished so as to form a gap depth.
A composite type magnetic head thus produced has a structure shown in, for example, FIG.
4
.
In
FIG. 4
,
30
is a non-magnetic housing. In a condition that a core chip
29
is fixed to the housing
30
, a coil
31
is set so as to form a slider
36
. To the slider
36
having a coil
31
is connected a suspension
32
for generating a force toward a medium. To the suspension is fixed a tube
33
for insulating and protecting a lead wire
35
. In this condition, a magnetic head
37
is constituted.
The magnetic head
37
floats at a minute intervals on the medium by a balance of a floating force and a pressure
4
from the slider
36
to the medium by the suspension
32
. The floating force is generated between a sliding surface and the medium. Thus, the magnetic head
37
can move over the medium of the slider
36
at a high speed.
The smaller and lighter slider
36
is more preferable because a flowability is enhanced against a rough surface of the medium, the floating is more stable, a magnetic converting property is enhanced, and a speed-up of the movement of the slider
36
over the medium can be achieved. However, a size of the slider
36
is restricted by a size of a slit
34
. As seen from
FIG. 4
, since a wire is wound in a state that the slider
36
slides, the slider
36
is provided with a slit
34
for the winding. A size of the slit
34
is restricted by a size of a slider
36
. A size of the slit
34
is a maximum restrictive matter in the case that a size of the slider
36
is decreased. Accordingly, making a wire material for a coil thinner and making the coil smaller enables to miniaturization of the slider
36
, thereby improving a floating stability.
Thus, it is important to thin down a wire material for a coil in a composite type magnetic head, too.
SUMMARY OF THE INVENTION
The present invention aims to provide a wire material of a composite metallic wire the diameter of which is reduced and the tensile strength of which is enlarged so as to enable a wiring operation.
The present invention aims to provide also a composite type magnetic head which can cope with a memory density of 600 Mb/in
2
or more by using the aforementioned composite wire.
The present invention is intended to solve the above problems.
According to the present invention, there is provided a composite metallic wire comprising:
an inner layer having a cross-sectional shape of a rough circle; and
a metal outer layer having a cross-sectional shape of a rough ring;
wherein the composite metallic wire has a diameter of 15 &mgr;m or less and an electric resistance of 300 &OHgr;/m or less.
The composite metallic wire is preferably provided with an insulating coat in the outer periphery of the outer layer.
The composite metallic wire preferably has a diameter of 14 &mgr;m or less.
The inner layer is preferably constituted of a wire material having a diameter of 12 &mgr;m or less and a tensile strength of 15 g or more.
Further, the inner layer may be composed of a metallic material, a carbonaceous material, or an organic material.
Furthermore, the outer layer is preferably constituted of a material having a specific resistance of 6×10
−8
&OHgr;·m or less.
Furthermore, the composite metallic wire preferably has a tensile strength of 20 g or more.
According to the present invention, there is also provided a composite type magnetic head using as a coil wire a composite wire comprising:
a composite metallic wire comprising: an inner layer having a cross-sectional shape of a rough circle; and a metal outer layer having a cross-sectional shape of a rough ring; wherein the composite metallic wire has a diameter of 15 &mgr;m or less and an electric resistance of 300 &OHgr;/m or l

Affiliated with

Also associated with

Rating

Composite type magnetic head using composite metallic wire does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Composite type magnetic head using composite metallic wire, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composite type magnetic head using composite metallic wire will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2515313