Abrading – Precision device or process - or with condition responsive... – With indicating
Reexamination Certificate
1997-10-24
2001-03-06
Rose, Robert A. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
With indicating
C451S008000, C451S010000, C451S011000, C451S005000, C451S024000, C451S057000
Reexamination Certificate
active
06196897
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for automatically lapping a work piece and a lapping apparatus using the same. More particularly, it relates to a lapping method for continuously lapping the work piece and a lapping apparatus using the same.
For example, after forming a magnetic head thin film, the magnetic head thin film is lapped on the process of manufacturing a magnetic head. Heights of a magnetic resistance layer and a gap of the magnetic head thin film of the magnetic head are made to have a certain constant by lapping on the manufacturing process of the magnetic head.
For the heights of the magnetic resistance layer and the gap, sub-micron order of accuracy is required. Therefore, it is necessary to lap work pieces or magnetic thin films with high accuracy.
2. Description of the Related Art
FIGS. 21A and 21B
are explanatory diagrams of a composite type magnetic head.
As shown in
FIG. 21A
, the composite type magnetic head includes a magnetic resistance element
82
formed on a base plate
81
and a writing element
85
. The magnetic resistance element
82
is formed of a magnetic resistance film
83
and a pair of conducting films
84
as shown in
FIG. 21B. A
resistance value of the magnetic resistance element
82
is varied by an external magnetic field. The magnetic resistance element
82
has a function to read out an electric current having a value according to magnetic field strength of a track
90
on a magnetic disk.
As the magnetic resistance element
82
is an element for reading out the current, it is required to provide a different element
85
for writing. The writing element
85
includes an inductive head. The inductive head is comprised of a lower magnetic pole
86
, an upper magnetic pole
88
faced to the lower magnetic pole
86
with a certain gap, and a coil
87
provided between the lower and upper magnetic poles
86
and
88
to magnetically excite them. A non-magnetic insulating layer
89
is provided around the coil
87
.
In such the composite type magnetic head, it is required to have a constant resistance value of the magnetic resistance film
83
in the magnetic resistance element
82
for each magnetic head. However, it is difficult to make the resistance value be constant or uniform on the process of manufacturing the thin film for the magnetic head. Therefore, after forming the thin film of the magnetic head, a height (width) h of the magnetic resistance film
83
is adjusted so that a resistance value may be uniformed.
FIGS. 22A
,
22
B,
23
A,
23
B,
23
C and
23
D are diagrams explaining the process of manufacturing the composite type magnetic head.
As shown in
FIG. 22A
, a plurality of composite type magnetic heads are formed on a semiconductor wafer
100
by a thin film technique. Next, as shown in
FIG. 24B
, the wafer
100
is cut into strips to make a plurality of row bars
101
. A row bar
101
includes a plurality of the magnetic heads
102
arranged in one row. Resistance elements
102
a
are provided on the left and right ends, and at the center of the row bar
101
for monitoring the process of the manufacturing.
As described above, the height of the magnetic resistance film
83
for the magnetic head
102
is lapped to be constant or uniform. However, the row bar
101
is extremely thin, for example, about 0.3 mm. It is, therefore, difficult to mount the row bar
101
directly to a lapping jig, and as shown in
FIG. 22C
, the row bar
101
is bonded to a mounting tool or base
103
with heat dissoluble wax.
Then, as shown in
FIG. 23A
, the row bar
101
, which is bonded to the mounting base
103
, is placed on a lapping plate
104
for lapping the row bar
101
. As known in Japanese Unexamined patent application published No. 2-124262 (U.S. Pat. No. 5,023,991) or Japanese Unexamined patent application published No. 5-123960, the resistance value of the resistance element
102
a
for monitoring is always measured while lapping the row bar
101
. Then, it can be detected whether or not the magnetic resistance film of the magnetic head
102
has become a targeted height.
When it is detected by the measurement of the resistance value that the magnetic resistance film has been lapped to the targeted height, the lapping processing is stopped. After that, a slider can be formed on a bottom surface
101
-
1
of the row bar
101
, as shown in FIG.
23
B.
The row bar
101
is further cut into a plurality of magnetic heads
102
, as the row bar
101
is mounted on the mounting base
103
as shown in FIG.
23
C. Each magnetic head
102
is taken out from the mounting base
103
by heating and melting the heat dissoluble wax, as shown in FIG.
25
D.
In this way, a row bar
101
including a plurality of the magnetic heads
102
is prepared, and lap processing is performed for the row bar
101
. Therefore, the magnetic resistance film on the plurality of magnetic heads
102
can be lapped by one step.
FIG. 24
is an explanatory diagram of a conventional lapping apparatus.
The lapping apparatus has a rotary lapping plate
104
, as shown in
FIG. 24. A
supporting block
105
has three pads
105
a
contacting to the lapping plate
104
. The pads
105
a
smoothly spread slurry (abrasive liquid) on the lapping plate
104
and fill the slurry into the lapping plate
104
. The pads
105
a
, further, may soften pressure of the supporting block
105
to the surface of the lapping plate
104
.
The supporting block
105
is swung on the lapping plate
104
by a swing mechanism
106
. The supporting block
105
supports the mounting base
103
. Therefore, the row bar
101
, which is bonded to the mounting base
103
, is lapped by the rotation of the lapping plate
104
and the swing of the block
105
.
In the conventional lapping apparatus, speed and pressure on lapping process are set as to be constant from starting to finishing the process.
It has been possible to reduce the time required for the processing by increasing rotating times of a lapping plate or giving higher pressure. Thereby, it becomes possible to save the time for the lapping process. However, there has been a problem to lower quality of lapping when the processing speed is increased.
On the other hand, when the speed for the lapping process is decreased to obtain good quality of lapping, there would be another problem to take much time for the lapping process.
It may be considered that a first lapping apparatus for speeding the processing up and a second lapping apparatus for speeding the processing down are employed together. After executing a coarse processing in the first lapping apparatus, a fine processing is performed by the second lapping apparatus. However, the work piece has to be set on the lapping apparatus twice according to the method, and therefore, troublesome for an operator and take much time. Therefore, it is unsuitable for mass production of the work pieces.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an automatic lapping apparatus to save processing time and realize quality of lapping process and a lapping apparatus using the same.
It is another object of the present invention to provide a lapping method for automatically changing coarse processing and fine processing and a lapping apparatus using the same.
It is further object of the present invention to provide a lapping method for automatically changing coarse processing and fine processing according to a remaining amount of processing the work piece and an apparatus using the same.
REFERENCES:
patent: 5203119 (1993-04-01), Cole
patent: 5486129 (1996-01-01), Sandhu et al.
patent: 5525091 (1996-06-01), Lam et al.
patent: 5579717 (1996-12-01), Crandell et al.
patent: 5720845 (1998-02-01), Liu
patent: 5733177 (1998-03-01), Tsuchiya et al.
patent: 5749769 (1998-05-01), Church et al.
patent: 5876264 (1999-03-01), Church et al.
Sugiyama Tomokazu
Suto Koji
Watanuki Motoichi
Yanagida Yoshiaki
Yokoi Kazuo
Fujitsu Limted
Greer Burns & Crain Ltd.
Rose Robert A.
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