Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-10-05
2001-03-06
Hall, Carl E. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603120
Reexamination Certificate
active
06195871
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing magnetic head elements (MR/GMR head elements), in which the width of ELG (Electric Lapping Guide) elements for monitoring the lapping process can be narrow so as to the increase number of magnetic head elements that can be manufactured.
Magnetic head elements used in magnetic disk drive units, and similar devices, are manufactured by forming magnetic layers, non-magnetic layers, and other layers on a wafer-shaped ceramic substrate. A plurality of sensing portions, each including a magnetic resistance effect head (a reading head) including an MR element an electromagnetic converting head (a recording head), and terminals (pads) connected thereto are formed on the substrate.
The magnetic head elements are formed by the steps of:
forming magnetic head element sections and terminals in the substrate; dividing the wafer into thin bar-shaped members
10
(see FIG.
6
); and lapping a side face of the bar-shaped member (work piece). The bar-shaped member
10
is made by cutting the wafer, and tens of magnetic head element sections
12
are arranged therein.
The side face of the bar-shaped member
10
is lapped so as to adjust height (MR height) of the sensing portions including the layered MR elements, etc. to a prescribed height. If the height of the sensing portions is lower, the sensivity thereof can be higher. These days, the required MR height of the magnetic head element is 0.8 &mgr;m±0.2 &mgr;m, and it will be 0.4 &mgr;m±0.05 &mgr;m in the future.
As described above, the manufacturing accuracy of the sensing portions is extremely high, so lapping the bar-shaped member
10
a problem. In a conventional method, ELG elements are used when the bar-shaped member
10
is lapped.
In the bar-shaped member
10
, each ELG element section
14
is adjacent to each magnetic head element section
12
. Each ELG element
14
is used to control the amount of lapping of the adjacent magnetic head element section
12
.
As described above, tens of the magnetic head element sections
12
are formed in the bar-shaped member
10
, and high machining accuracy is required for each element section. Thus, the ELG element
14
is adjacent to the side of each magnetic head element section
12
so as to control the amount of lapping for each magnetic head element section
12
and to increase the machining accuracy.
In
FIG. 6
, reference numerals
16
stand for the element portions of the magnetic head element sections
12
. Connecting pads
18
a
and
18
b
for reproducing, and connecting pads
20
a
and
20
b
for recording are formed on a surface of the bar-shaped member
10
.
Pads
22
a
and
22
b
are formed on a surface of the ELG element
14
.
FIG. 7
is a sectional view of the ELG element
14
taken along line A-A′ in
FIG. 6
;
FIG. 8
is a sectional view of the ELG element
14
taken along line a-a′ in FIG.
6
.
A non-magnetizable substrate, e.g., an Al
2
O
3
TiC substrate, is provided and a protecting layer
26
which is made of, for example, alumina, is formed on the substrate
25
.
A lower shielding layer
27
, which is made of sendust, is formed on the protecting layer
26
. An alumina layer
28
, which acts as a read-gap, is formed on the lower shielding layer
27
. The MR element portions (sensing portions)
30
, which are well known, are formed on the alumina layer
28
.
Hard layers
31
, for controlling magnetic domains, are made of CoCrPt, and they are respectively connected to both ends of each MR element portion
30
. Lead layers
32
, which are made of, for example, copper, are formed on the hard layers
31
.
Terminal pillars
33
, which are made of, for example, copper, are respectively formed at ends of the lead layers
32
as shown in FIG.
8
.
The terminal pillars
33
are formed by plating holes in resist layers (not shown). The resist layers are removed.
An alumina layer
35
, which acts as read-gaps and write-gaps, is formed on the alumina layer
28
and the lead layers
32
.
An overcoating alumina layer
36
covers over the alumina layer
35
and the terminal pillars
33
to protect them.
The overcoating alumina layer
36
will be lapped until the terminal pillars
33
are exposed, then the monitor pads
22
a
and
22
b
, which are made of gold, will be formed on the exposed upper end faces of the terminal pillars
33
.
The magnetic head element sections
12
are formed on the non-magnetizable substrate
25
, by a known manner. In particular, the layer-structures of the sensing portions are almost the same as those of the ELG elements
14
.
The connecting pads
18
a
and
18
b
are connected to the sensing part (not shown), which includes the MR element of the element portion
16
via the terminal pillars
38
(shown by dotted lines in FIG.
6
). These pads
18
a
and
18
b
, as well as the terminal pillar
33
on the ELG element
14
side, inner lead layers
39
are made of, for example, copper.
The connecting pads
20
a
and
20
b
are connected to a thin coil layer (not shown) of the element portion
16
via the terminal pillars
41
(shown by dotted lines in FIG.
6
). These pads are made of copper, for example, are as the terminal pillar
33
on the ELG element
14
side, and inner lead layers
41
.
The bar-shaped member
10
is secured in a proper jig (not shown) and the side face P (see
FIG. 6
) is lapped. The MR element portions of the ELG elements
14
and the MR element portions of the magnetic head element sections
12
are simultaneously lapped. The jig has pressing means (not shown) capable of respectively pressing the magnetic head element sections
12
and the ELG elements
14
onto lapping means, and the lapping speed is adjusted so as to simultaneously complete the lapping work of all the magnetic head elements
12
.
While performing the lapping work, the ELG elements
14
are connected to a monitor means (not shown) by the pads
22
a
and
22
b
, and the change in resistance of the MR element portions
30
, which changes while lapping the MR element portions
30
, is detected. The shape of the MR element portion of the magnetic head element section
12
and the shape of the MR element portion of the ELG element
14
should be same or very similar. By detecting the change in resistance of the MR element portions
30
, the change of the resistance of the MR element portions of the magnetic head element sections
12
can be known, so that the lapping work is executed until the MR height of the MR element portions of the magnetic head element sections
12
reach a prescribed height.
By placing the ELG elements
14
adjacent to the magnetic head element sections
12
for monitoring purposes, the MR height can be controlled with higher accuracy.
After the lapping work, the bar-shaped member
10
is cut along the ELG elements
14
to divide the member
10
into a plurality of magnetic head element sections
12
.
Since the ELG elements
14
are used for monitoring purposes only and are removed from the final products, width of the ELG elements
14
should be narrow so as to manufacture many magnetic head element sections
12
in one bar-shaped member
10
.
FIG. 9
shows a state in which the overcoating alumina layer
36
is formed to cover the terminal pillars
33
,
38
and
41
after the terminal pillars
33
,
38
and
41
, whose height are about
20-30
&mgr;m, are formed. When the overcoating alumina layer
36
is formed by spattering, abnormal layers
37
(shown by dotted lines) are formed beside the terminal pillars
33
,
38
and
41
due to step coverage thereof.
If separations between the terminal pillars
33
,
38
and
41
are narrow, the abnormal layers
38
are high (see FIG.
10
), and holes are opened when the terminal pillars are exposed by lapping. Note that, a line Q indicates a lapping face. To prevent forming the holes, the separations between the terminal pillars should be at least 100 &mgr;m.
When the ELG elements
14
are cut, if the abnormal layers
37
are cut, chipping occurs because the abnormal layers are weak. To avoid chipp
Fujitsu Limited
Greer Burns & Crain Ltd.
Hall Carl E.
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