Abrading – Machine – Rotary tool
Reexamination Certificate
1999-11-16
2001-05-29
Hail, III, Joseph J. (Department: 3723)
Abrading
Machine
Rotary tool
C451S005000, C451S009000, C451S010000, C451S041000, C451S063000, C451S270000
Reexamination Certificate
active
06238276
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sizing lapping apparatus which can perform lapping operations with high precision when, for example, a slider of a floating-type magnetic head used in a magnetic disk unit is produced by lapping.
2. Description of the Related Art
An increase in the recording density of magnetic disks has encouraged the production of smaller and lighter floating-type magnetic head sliders used in magnetic disk units, year after year. At present, thin-film magnetic heads are primarily used. In such thin-film magnetic heads, the magnetic gap portion has a very fine structure, making the precision of lapping operations carried out during the manufacturing process a very important factor in determining the quality of the magnetic heads that have been manufactured.
In manufacturing such magnetic head sliders, a plurality of films are deposited on one piece of wafer by a deposition method, during which required circuits are written by a lithography technique in order to form a plurality of thin-film magnetic heads on the piece of wafer at the same time. Then, the plurality of thin-film magnetic heads are sliced from the piece of wafer, whereby the plurality of thin-film magnetic heads are mass-produced. Accordingly, in this manufacturing method, when the thin-film magnetic heads are not precisely processed when they are sliced from the wafer, magnetic head yield may be considerably reduced.
Hitherto, in the case where thin-film magnetic heads are mass-produced by slicing them from a wafer, the gaps of the magnetic gap portions of the thin-film magnetic heads had been formed by the following method.
As illustrated in
FIG. 10
, a plurality of thin-film magnetic head devices are formed in rows on a wafer
1
, which is sliced in a horizontal direction (in
FIG. 10
) to obtain a sliced-out bar
2
(shown in FIG.
11
). As shown in
FIG. 12
(which is an enlarged view of the bar
2
), a plurality of thin-film magnetic head devices
5
are formed in a row on the bar
2
. Each thin-film magnetic head device
5
shown in
FIG. 12
comprises a coil portion
6
; and four electrode pads
7
that are arranged at one side of its corresponding coil portion
6
. To the electrode pads
7
are connected lead wires extending from the corresponding coil portion
6
and lead wires extending from an internal circuit of the corresponding thin-film magnetic head devices
5
.
FIG. 13
illustrates an enlarged view of a thin-film magnetic head device
5
of FIG.
12
. In the structure of the thin-film magnetic head, the depth to which the gap of a magnetic gap portion g, formed adjacent to the end portion of the coil portion
6
, is formed is very important because it directly determines the performance of the thin-film magnetic head
5
. Therefore, the bar
2
is mounted to a sizing lapping apparatus in order to lap the top surface of the bar
2
precisely.
In the case where the thin-film magnetic head is a GMR head using a huge magnetoresistive effect element (GMR element), the depth of the gap portion of a read/write head (for reading and writing magnetic signals), the throat height (equivalent to the length of an end portion of a magnetic pole of the read/write head), and the MR height (equivalent to the depth of the gap portion of the read/write head) all depend upon the precision with which the lapping surface is lapped. In addition, both gap portions need to be lapped together. Therefore, it is necessary to achieve very precise lapping operations.
Conventional sizing lapping apparatuses comprise a lap plate, to which a lapping liquid is supplied. In general, when lapping operations are carried out by conventional sizing lapping apparatuses, the lap plate is rotated while a workpiece is pressed against it. In the case where a member such as that in which a sliced bar
2
having a plurality of thin-film magnetic head devices
5
formed thereon is to be lapped precisely, lapping precision may not be satisfactory. In recent years, there has tended to be a demand for such thin-film magnetic heads, in particular, to be lapped very precisely to an order equal to or less than ±0.1 &mgr;m.
The plurality of thin-film magnetic head devices
5
are formed on the sliced bar
2
by a deposition method. Although they are arranged very precisely on the wafer
1
, they may go out of alignment due to bending or deformation of the bar
2
sliced from the wafer
1
. Even in such a case there has been a demand for high-performance sizing lapping apparatuses which can perform lapping operations with high precision.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a high-performance sizing lapping apparatus which can perform lapping operations with very high precision. It is another object of the present invention to provide a sizing lapping apparatus which can perform lapping operations very precisely by partly controlling the amount by which the workpiece is lapped in accordance with the lapping condition thereof. It is still another object of the present invention to provide an apparatus which can perform lapping operations very precisely by correcting workpiece bending.
To these ends, according to the present invention, there is provided a sizing lapping apparatus comprising a rotatably provided disk-shaped lap plate for supplying a lapping liquid thereto; at least one holding portion for holding a workpiece, the at least one holding portion being used to press the workpiece against the lap plate; a support shaft, provided in an erected state with respect to the lap plate, for supporting the at least one holding portion; an oscillating mechanism for causing the support shaft to undergo oscillatory rotational motion around an axis thereof; a base for supporting the support shaft so that the support shaft freely rotates around the axis thereof; and a base rocking mechanism for reciprocating the base in a diametrical direction of the lap plate or in a direction substantially parallel to the diametrical direction of the lap plate.
The support shaft that supports the at least one holding portion may oscillate freely around the axis thereof at an angle within a range equal to or less than 90 degrees and alternately towards the left and right.
In the case where the support shaft that supports the at least one holding portion oscillates freely around the axis thereof at an angle within a range equal to or less than 90 degrees and alternately towards the left and right, the holding portion that supports the workpiece may comprise a correction jig having the workpiece mounted thereto; a mounting jig for gripping the correction jig; and a pressing mechanism for freely pressing towards the lap plate a center portion side and both end portion sides of the correction jig by separate pressing forces.
In the case where the holding portion that supports the workpiece comprises a correction jig having the workpiece mounted thereto; a mounting jig for gripping the correction jig; and a pressing mechanism for freely pressing towards the lap plate a center portion side and both end portion sides of the correction jig by separate pressing forces, the holding portion may have provided thereat a plurality of rods which separately and freely move closer to and away from the lap plate, with the rods freely and separately pressing against the lap plate both end portion sides and a center portion side of the workpiece supported by the holding portion.
In the case where the holding portion has provided thereat a plurality of rods which separately and freely move closer to and away from the lap plate, with the rods freely and separately pressing against the lap plate both end portion sides and a center portion side of the workpiece supported by the holding portion, the holding portion may further have provided thereat a mounting jig having the workpiece secured thereto, with a dummy head for balancing and adjusting lapping operations being mounted at the mounting jig, and with a point to which pressure is applied towards the lap pl
Miyazaki Masaharu
Nakabayashi Isao
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Hail III Joseph J.
McDonald Shantese
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