Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2000-02-22
2001-12-11
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
Reexamination Certificate
active
06330132
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head having an enhanced bonding strength between a lead wire and a conductive member and having improved reliability, in which the lead wire leads from a head element of a thin film magnetic head and the like, and the conductive member exchanges electrical signals with the head element.
2. Description of the Related Art
As shown in
FIG. 9
, the front portion of a flexure
2
is cut away in the form of an approximately U-shape to form a small portion
2
a,
and four conductive patterns
3
composed of copper and coated with gold by plating thereon are formed on the surface of the flexure
2
coated by a polyimide resin.
End portions
3
a
of the conductive patterns
3
are formed so as to broaden and are lined up on the small portion
2
a.
A slider
1
in the form of a rectangular parallelepiped is fixed by bonding at a bottom surface
1
b
thereof on the small portion
2
a
of the flexure
2
so that the end portions
3
a
of the conductive patterns
3
oppose a side wall
1
a
of the slider
1
.
As shown in FIG.
10
and
FIG. 11
, the side wall
1
a
of the slider
1
has a head element
7
for writing on and/or reading from a magnetic recording medium, and four lead wires
8
, two for writing and two for reading, lead from the head element
7
. An edge
8
a
of each lead wire
8
having a wider area in an approximately rectangular form is formed in the vicinity of the surface of the flexure
2
. Individual edges
8
a
of the four lead wires
8
are disposed so as to oppose the corresponding end portions
3
a
of the conductive patterns
3
in the vicinity thereof.
As shown in
FIG. 11
, a bump
10
composed of nickel or the like is provided on the edge
8
a
of the lead wire
8
. The bump
10
is composed of a cylindrical pillar portion
10
a
having the bottom surface contacting nearly the entire edge
8
a
of the lead wire
8
and an umbrella-like portion
10
b
expanding at the front edge of the pillar portion
10
a.
The umbrella-like portion
10
b
of the bump
10
has an excavated top at the top of approximately hemispherical form, and a round area at the center of the umbrella-like portion
10
b
is to be used as a contact area
10
d
of the bump
10
.
The contact area
10
d
of the bump
10
has an inclined portion
10
f
at the periphery thereof and is recessed into the spherical portion
10
e
of the umbrella-like portion
10
b.
A protective layer
9
composed of alumina covers the head element
7
, the lead wires
8
, and the surfaces of the pillar portions
10
a
and the spherical portions
10
e
of the bumps
10
on the side wall
1
a,
and is formed so as to be flat. The surface of the contact area
10
d
of the bump
10
is exposed from the protective layer
9
, and is recessed from the level of the surface of the protective layer
9
since the inclined portion
10
f
exists at the boundary of the protective layer
9
.
The contact area
10
d
of the bump
10
exposed from the protective layer
9
is adjacent to the surface of the flexure
2
.
In a polishing process for polishing the protective layer
9
so as to expose the contact area
10
d
of the bump
10
, the form of the umbrella-like portion
10
b
of the bump
10
as described above is formed by polishing the top of the approximately hemispherical umbrella-like portion
10
b
of the bump
10
together with the protective layer
9
.
In the polishing process, the bump
10
composed of a metal, such as nickel, is easily polished since the bump
10
is softer than the protective layer
9
composed of alumina, so that the contact area
10
d
of the bump
10
exposed from the protective layer
9
has the inclined portion
10
f
at the boundary of the protective layer
9
and is recessed from the level of the surface of the protective layer
9
.
Four rectangular pads
11
composed of thin gold films or the like cover the surfaces of the individual contact areas
10
d
of the four bumps
10
exposed from the protective layer
9
, and are disposed so as to oppose the corresponding end portions
3
a
of the conductive pattern
3
on the surface of the flexure
2
adjacent to each other.
The pads
11
includes a recessed portion
11
a
covering the surface of the contact area
10
d
of the bump
10
and an inclined portion
11
f
overlaying an inclined portion
10
f
of the bump
10
from the contact area
10
d
thereof to the surface of the protective layer
9
.
Since the contact area
10
d
of the bump
10
is adjacent to the surface of the flexure
2
, the recessed portion
11
a
of the pad
11
and the inclined portion
11
f
thereof are also adjacent to the end portion
3
a
of the conductive pattern
3
formed on the surface of the flexure
2
.
At an angular portion
12
at which the side wall
1
a
of the slider
1
and the surface of the flexure
2
contact each other, an approximately spherical bonding member
13
, composed of gold or the like, is joined in contact with the recessed portion
11
a
of the pad
11
and the end portion
3
a
of the conductive pattern
3
, so that the pad
11
and the conductive pattern
3
are connected to each other. On the surface of the approximately spherical bonding member
13
, a protruding residual portion
13
a
remains.
As shown in
FIGS. 12 and 13
, there is a conventional example in which wire
15
is used as the bonding member, and in which an edge portion
15
a
of the wire
15
is bonded to the recessed portion
11
a
of the pad
11
, and the other edge portion
15
b
of the wire
15
is bonded to the end portion
3
a
of the conductive pattern
3
.
In the magnetic head described above, the surface of the slider
1
is disposed so as to oppose the magnetic recording surface of the magnetic disc, and the slider
1
fixed to the flexure
2
is raised at a predetermined distance over the magnetic recording surface of the magnetic disc during an operation of the magnetic hard disc. The head element
7
is connected to an external circuit through the lead wires
8
, the bumps
10
, and the conductive patterns bonded by the bonding members to the bumps
10
via the pads
11
so as to perform magnetic writing on and reading from the magnetic disc by transmission of electric signals of electric circuits from the head element
7
to the external circuit.
In a bonding process for bonding the pad
11
and the conductive pattern
3
by using the spherical bonding member
13
, as shown in
FIG. 14
, a front edge of a fine gold wire
17
drawn from a capillary
16
for bonding is melted by discharging, whereby the spherical bonding member
13
is formed. When the bonding member
13
contacts the recessed portion
11
a
of the pad
11
and the surface of the end portion
3
a
of the conductive pattern
3
, ultrasonic vibration is imparted to the bonding member
13
, and the bonding member
13
is bonded to the pad
11
and to the end portion
3
a
of the conductive pattern
3
by ultrasonic welding.
In this case, since the pad
11
has the recessed portion
11
a
adjacent to the end portion
3
a
of the conductive pattern
3
in the conventional magnetic head, depending on the size of the spherical bonding member
13
, the bonding member
13
may be bonded to the end portion
3
a
of the conductive pattern
3
and an angular portion of the inclined portion
11
f
of the pad
11
, as shown in FIG.
15
. Consequently, there is a problem in that contact defects between the bonding member
13
and the pad
11
may occur.
When the spherical bonding member
13
rotates along the inclined portion
11
f
of the pad
11
, as shown in
FIG. 16
, the bonding member
13
is placed at the pad
11
side and is raised from the end portion
3
a
of the conductive pattern
3
, so that there is a problem in that contact failure with the conductive pattern
3
may occur.
When the bonding member for bonding the pad
11
and the conductive pattern
3
is the wire
15
, as shown in
FIGS. 12 and 13
, the front edge portion
15
a
of the wire
15
is contacted to the recessed portion
11
a
of the
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Evans Jefferson
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