Abrading – Abrading process – Utilizing fluent abradant
Reexamination Certificate
2000-03-30
2002-06-04
Hail, III, Joseph J. (Department: 3723)
Abrading
Abrading process
Utilizing fluent abradant
C451S041000, C125S012000, C125S020000, C083S651100
Reexamination Certificate
active
06398623
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of working a device and a method of working a slider. More particularly, the invention relates to a method of working a device and a method of working a slider for cutting and individually separating devices or sliders which are formed on one substrate and require smoothness of the side and front surfaces thereof.
2. Description of the Related Art
A slider for a magnetic head for use in a magnetic recording apparatus such as a hard disc driver (hereinafter referred to as HDD) is manufactured through steps generally shown in
FIGS. 8A
to
8
F, for example.
First, a plurality of devices
1
such as a transducer having a function of writing/reading information as the magnetic head are formed on a substrate
2
such as a ceramic substrate (see FIG.
8
A).
Then, the substrate
2
is cut so as to be rectangular (see FIG.
8
B). Then, the rectangular substrate
2
is further sliced into bars, each of which has a line of about ten or more devices
1
horizontally arranged, and bars
3
are separated from one another (see FIG.
8
C). Heretofore, such cutting has been generally performed by using a diamond peripheral cutting edge. Then, each of the separate bars
3
is stuck on a suspension
4
with wax (not shown) or the like (see FIG.
8
D). Sticking is temporary bonding such that the sliders can be separated from the suspension
4
after the sliders are completely individually separated from one another in the following step.
Then, each of the devices
1
arranged on the bar
3
is worked as the slider. That is, a head slider surface is ground, structures such as a groove for determining a width of a slider rail and a bleed slot surface are worked, and a head levitation surface, i.e., a slider rail surface is polished so as to have predetermined surface roughness of 0.05 &mgr;m or less, for example. Furthermore, an air inlet for functioning as an air bearing surface of the slider rail surface is tapered (see FIG.
8
E).
After the structure of a principal part of the slider is thus formed, sliders
6
, each of which comprises each of the devices
1
worked in a unit of the bar
3
, are separated one by one by cutting the bar
3
at a boundary between adjacent sliders
6
(see FIG.
8
F).
Then, chamfering (so-called blending) takes place (not shown). In order to prevent the slider from doing damage to the surface of a magnetic recording medium (a magnetic disk) at the time of contact start/stop when the slider mounted as a slider head is used in the HDD, chamfering is applied to more particularly an edge of the slider rail surface which is likeliest to contact the surface, additionally an edge line portion which is likely to contact the surface of the magnetic recording medium (the magnetic disk) and so on. Heretofore, the slider for the magnetic head for use in the magnetic recording apparatus such as the HDD has been manufactured through such a manufacturing process.
In the above-described step of working the slider for the magnetic head of the related art, more particularly, in the step of individually separating the sliders by cutting the bar
3
, cutting is generally done by using a diamond sharp edge grinding wheel (a diamond peripheral cutting edge saw).
However, such a cutting method of the related art using the diamond sharp edge grinding wheel has the following various problems. That is, the cutting method itself using the diamond sharp edge grinding wheel essentially has mechanical characteristics of cutting the bar
3
while applying a large shearing force to the bar
3
, and thus a surface cut by the diamond sharp edge grinding wheel results in a crushed surface or a streaked surface. The surface roughness of the cut surface that is the crushed surface or the streaked surface can only be smoothed to about 20 nm in terms of Ra even through an approach of reducing roughness of the diamond sharp edge grinding wheel and others. So-called contamination such as external dust or particles or dust produced within the HDD itself is prone to adhere to such a rough surface.
Therefore, a problem exists. During the use of the HDD, such contamination peels off due to vibration generated during operation of the slider head, vibration created during carrying of the HDD itself or the like, and the contamination adheres to the surface of the magnetic disk that is the recording medium, or the contamination is attracted into a gap between the magnetic disk and the slider. Consequently, the contamination damages the surface of the magnetic disk.
There exists another problem. Adhesion of contamination to the surface of the magnetic disk causes a record or read malfunction such as a read/write error resulting from thermal asperity. Moreover, in the cutting method using the diamond sharp edge grinding wheel, the cut surface has the crushed surface or the streaked surface as described above. In other words, the fact that the cut surface has the crushed surface or the streaked surface means that cutting takes place while such a large shearing force is applied to the bar
3
. Accordingly, high stress is applied to the bar
3
due to such a large shearing force applied during cutting. As a result, the overall shape of the cut bar
3
remains under stress strain.
Thus, the individual sliders obtained through cutting have a problem: various failures deteriorating profile precision for the slider occur. Failures include malformation, namely, convex or concave warping called a crown; poor inclination along the width of the slider rail of the air bearing surface, called a camber; poor parallelism along a length of two slider rails of the air bearing surface, called a twist (i.e., the relative positions of two slider rails are in a state in which two slider rails are not parallel to each other but twisted); and so on.
More particularly, in recent years, a further increase in an information recording density has been strongly demanded. The increase in the information recording density requires a further reduction in magnetic spacing. The reduction in the magnetic spacing is accomplished by more precisely controlling and thus further reducing a height of levitation of the slider from the recording medium. An approach of reducing a conventional height of levitation of about 40 nm to 50 nm by more than half, i.e., to about 10 nm to 20 nm and others have been also proposed. In order to realize the purpose, it is therefore strongly demanded that the air bearing surface (hereinafter referred to as ABS) is more highly precise, roughness-free, smooth and flat.
However, the cutting method of the related art using the diamond sharp edge grinding wheel has a problem of being unable to cope with a further improvement in precision of the ABS for a recent increase in the information recording density because various failures deteriorating the profile precision for the slider occur as described above.
Moreover, due to a large shearing force applied to the bar
3
during cutting as described above, protrusions of about 2 nm to 10 nm or asperities are produced at an edge at which the cut surface crosses the surface of the ABS. There is a problem that the protrusions or asperities also cause deterioration in the profile precision for the slider similarly to the above-mentioned various malformations. Although the precision of the ABS generally needs a cross crown of 10 nm or less in order to improve stability of levitation of the slider and increase the information recording density, the cutting method of the related art using the diamond sharp edge grinding wheel has a problem of being unable to cope with the need.
Moreover, the following problem exists. Chippings of about 1 nm to 20 nm are produced at the edge at which the surface of the ABS crosses the cut surface obtained by the diamond sharp edge grinding wheel and the edge at which a rear surface opposite to the ABS crosses the cut surface obtained by the diamond sharp edge grinding wheel. Similarly to the above-mentioned contamination such as dust, the chippings peel off the slide
Fujii Ryuji
Fukuroi Osamu
Berry Jr. Willie
Oliff & Berridg,e PLC
TDK Corporation
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