Abrading – Precision device or process - or with condition responsive... – With feeding of tool or work holder
Reexamination Certificate
2000-01-18
2001-11-13
Hail, III, Joseph J. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
With feeding of tool or work holder
C451S005000, C451S278000, C451S279000
Reexamination Certificate
active
06315636
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a lapping machine, row tool, and lapping method for use in lapping a workpiece, and more particularly to a lapping machine, row tool, and lapping method suitable for mass production of magnetic heads uniform in quality.
2. Description of the Related Art
In a manufacturing process for a magnetic head, for example, a magnetic head thin film is formed on a substrate and next subjected to lapping, thereby making constant the heights of a magnetic resistance layer and a gap in the magnetic head thin film. The heights of the magnetic resistance layer and the gap are required to have an accuracy on the order of submicrons. Accordingly, a lapping machine for lapping the magnetic head thin film is also required to have a high working accuracy.
FIGS. 1A and 1B
illustrate a composite magnetic head in the related art. As shown in
FIG. 1A
, the composite magnetic head has a magnetic resistance element
2
formed on a substrate
1
and a write element
5
. As shown in
FIG. 1B
, the magnetic resistance element
2
is composed of a magnetic resistance film
3
and a pair of conductor films
4
connected to the opposite ends of the magnetic resistance film
3
. The magnetic resistance element
2
is an element whose resistance changes according to an external magnetic field. Accordingly, by using the magnetic resistance element
2
, an electric current having a magnitude corresponding to the magnetization of a track T on a magnetic disk, for example, can be output to thereby allow reading of data recorded on the magnetic disk.
The magnetic resistance element
2
is capable of reading data only. Therefore, the write element
5
is additionally provided to write data as required. The write element
5
is an inductive head, for example. The write element
5
has a lower magnetic pole
6
and an upper magnetic pole
8
opposed to the lower magnetic pole
6
with a gap defined therebetween. A coil
7
is provided between the lower magnetic pole
6
and the upper magnetic pole
8
to excite these magnetic poles
6
and
8
. The coil
7
is surrounded by a nonmagnetic insulating layer
9
.
In such a composite magnetic head, it is desirable to make constant the resistance of the magnetic resistance film
3
of the magnetic resistance element
2
. However, it is difficult to make the resistance constant only in a manufacturing process for the thin film of the magnetic head. Accordingly, after forming the thin film of the magnetic head, it is machined so that the height (width) h of the magnetic resistance film
3
becomes constant, thus obtaining a constant resistance.
FIGS. 2A
to
2
C and
3
A to
3
D illustrate a manufacturing process for the composite magnetic head shown in
FIGS. 1A and 1B
.
As shown in
FIG. 2A
, a set of many row bars
11
each having a plurality of composite magnetic heads
12
are formed on a wafer
10
by a thin-film technique. In the next step, the wafer
10
is cut into many rectangular parts to thereby separate the above set into the row bars
11
. As shown in
FIG. 2B
, each row bar
11
has a plurality of magnetic heads
12
and three resistance elements
12
a
for monitoring of lapping. These magnetic heads
12
and resistance elements
12
a
are arranged in a line. For example, the resistance elements
12
a
are positioned at the left end, center, and right end of the row bar
11
.
Each row bar
11
having the plural magnetic heads
12
is next subjected to lapping, so that the height of the magnetic resistance film
3
in each head becomes constant as mentioned above. However, since the row bar
11
is as thin as 0.3 mm, for example, it is difficult to mount the row bar
11
directly on a lapping machine. Accordingly, as shown in
FIG. 2C
, the row bar
11
is temporarily bonded to a row tool
13
by means of a hot-melt wax.
In the next step, the row bar
11
bonded to the row tool
13
is lapped on a lap plate
14
as shown in FIG.
3
A. In this lapping operation, the resistance of each resistance element
12
a
of the row bar
11
is measured all the times as known from U.S. Pat. No. 5,023,991 and Japanese Patent Laid-open No. Hei 5-123960, for example. Then, whether or not the height of the magnetic resistance film of each magnetic head
12
has become a target value is detected according to the measured resistance of each resistance element
12
a.
At the time it is detected that the magnetic resistance film has been lapped up to the target height, according to the measured resistance, the lapping operation is stopped. Thereafter, as shown in
FIG. 3B
, a slider is formed on a lower surface
11
-
1
of the row bar
11
.
In the next step, the row bar
11
is cut into the plural magnetic heads
12
in the condition that it is bonded to the row tool
13
as shown in FIG.
3
C. In the next step, the row tool
13
is heated to melt the hot-melt wax, thereby removing the magnetic heads
12
from the row tool
13
to obtain the individual magnetic heads
12
.
In this manner, the row bar
11
having the plural magnetic heads
12
arranged in a line is first prepared, and next subjected to lapping, so that the magnetic resistance films
3
of the plural magnetic heads
12
can be lapped at a time.
However, there are variations in height among the magnetic resistance films
3
of the plural magnetic heads
12
in the row bar
11
on the order of submicrons, depending on a mounting accuracy, film forming accuracy, etc. It is accordingly necessary to correct such variations in the lapping operation for mass production of magnetic heads uniform in characteristics.
In this respect, it is known in a related art that a hole is formed through the row tool
13
at a position near a work surface to which the row bar
11
is bonded, and that a force is applied from an actuator through this hole to the row tool
13
, thereby producing a desired pressure distribution between the row bar
11
and a lapping surface of the lap plate
14
. However, since the hole of the row tool
13
is singular, the variations cannot be reduced and it is difficult to obtain a high working accuracy.
To cope with this problem, it has been proposed to form a plurality of holes through the row tool
13
and apply forces from actuators through these holes, respectively to operate the row tool
13
as described in U.S. Pat. No. 5,607,340. However, these actuators are required to have capacities of applying relatively large forces to each one of these holes for obtaining a desired pressure distribution, it is therefore difficult to manufacture such actuators acting on a plurality of load points. As a result, the spacing between any adjacent ones of the plural load points (the plural holes) cannot be greatly reduced, yet causing a difficulty of improvement in working accuracy.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a lapping machine, row tool, and lapping method suitable for improvement in working accuracy.
In accordance with a first aspect of the present invention, there is provided a lapping machine for lapping a row bar for obtaining a plurality of head sliders. The lapping machine comprises a lap plate for providing a lapping surface, a row tool having a work surface for pressing the row bar against the lapping surface, and a mechanism for operating the row tool so that a given pressure distribution is produced between the row bar and the lapping surface. The row tool has a plurality of holes arranged along the work surface. The mechanism includes a plurality of pivoted links each having a load point where a force having a direction perpendicular to the work surface is applied to the row tool in each of the holes. Each of the pivoted links further has a support point as the fulcrum and an effort point where a force having a direction substantially parallel to the work surface is received. The ratio of a first distance between the load point and the support point to a second distance between the effort point and the support point is substantially constant.
With th
Nishioka Teruaki
Sone Shunsuke
Sudo Koji
Sugiyama Tomokazu
Yanagida Yoshiaki
Fujitsu Limited
Greer Burns & Crain Ltd.
Hail III Joseph J.
Ojini Anthony
LandOfFree
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