Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2000-04-13
2002-09-17
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S235400, C360S236600, C360S236700
Reexamination Certificate
active
06452750
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a slider for use in a magnetic recording apparatus or the like and a method of working a slider. More particularly, the invention relates to a slider, which is formed by simultaneously multi-bonding many sliders on one substrate and then individually separating the sliders and which requires smoothness of the side and front surfaces thereof, and a working method for cutting the sliders and thereby individually separating the sliders.
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. 14A
to
14
F, for example.
First, a plurality of devices
1
such as a transducer having a function of writing/reading information as the magnetic head is multi-bonded on a substrate
2
such as a ceramic substrate or a silicon wafer (see FIG.
14
A).
Then, the substrate
2
is cut so as to be rectangular in shape (see FIG.
14
B). Then, the rectangular substrate
2
is further sliced into bars, each of which has a horizontal array of about ten or more devices
1
, and bars
3
are individually separated from one another (see FIG.
14
C). Heretofore, such cutting has been generally performed by the use of a diamond peripheral cutting edge. Then, each of the separated bars
3
is stuck on a suspension
4
that is a jig, with wax (not shown) or the like (see FIG.
14
D). Sticking is adapted to be temporary bonding such that the devices
1
can be separated from the suspension
4
after the devices (sliders)
1
are completely individually separated from one another.
Then, each of the devices
1
arrayed on the bar
3
is worked as the slider. That is, a head slider surface is ground, structures functioning as the slider 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 (hereinafter referred to as ABS) of the slider rail surface is tapered (see FIG.
14
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.
14
F). Heretofore, cutting for separating has been also generally done by the use of the diamond peripheral cutting edge.
Then, chamfering (so-called blending) takes place (not shown). In order to prevent the slider from damaging the surface of a magnetic recording medium (a magnetic disk) at the time of contact start/stop when the slider is mounted as a slider head and 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, chippings of about 1 &mgr;m to 5 &mgr;m are, however, produced more particularly at the edge where the surface of the ABS crosses a cut surface obtained by a diamond sharp edge grinding wheel and the edge where a rear surface opposite to the ABS crosses the cut surface obtained by the diamond sharp edge grinding wheel.
The chippings have a problem. Similarly to contamination such as dust, the chippings peel off the slider due to vibration, shock or the like during the use of the HDD, and thus the chippings damage the surface of the magnetic disk as the contamination or cause malfunction such as a read/write error resulting from thermal asperity.
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 an amount of magnetic spacing by more precisely controlling and 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 reduced height of levitation with high precision, it is therefore strongly demanded that the ABS is formed with higher accuracy of dimension.
There is a tendency to further reduce the height of levitation of the slider. However, even particles finer than conventional particles enter into a fine gap. Thus, the particles are likelier to damage the surface of the magnetic disk and the surface of the slider than the conventional particles.
When chippings as described above are at the edge line portion where the surface of the ABS crosses the cut surface obtained by the diamond sharp edge grinding wheel, when the edge portion itself has an acute angle, or when malformation due to asperities whose edge has an acute angle occurs at the edge, a contact of the edge with the surface of the magnetic recording medium (the magnetic disk) causes damage to the surface of the magnetic recording medium.
The HDD of the related art is manufactured in a clean room whose cleanness is comparable to the cleanness of class 100 or more for a process of manufacturing LSI in order to prevent contamination from entering the HDD at time of manufacturing. Moreover, an air filter is included in the HDD so as to cope with mainly external contamination. Such an approach allows coping with an entry of contamination during manufacturing and an entry of external contamination.
However, during manufacturing, the contamination produced by peeling of chippings as described above adheres to the cut surface still in the form of chipping. Thus, the chippings are not recognized as a cause of failures. Thus, the chippings are likely to cause malfunction at the time of an actual use of the HDD, but the chippings are not checked and are overlooked. At the time of the actual use of the HDD, the slider having the adhering chippings makes a relative movement over the nearly overall surface of the magnetic disk. Thus, the slider is always located on or near the magnetic disk whenever the chippings peel off. That is, almost all the particles of the peeling chippings always drop onto and adhere to the magnetic disk. Consequently, there is a problem that the particles produced by the peeling of the chippings are extremely likely to damage the surface of the magnetic disk or cause the read/write error as the contamination.
Thus, the chipping or the edge portion having acute angle causes various problems. In order to solve such problems, it is extremely important to chamfer more particularly the edge of the slider. A blending method using a lapping tape disclosed in Japanese Patent Application No. Hei 10-104235 and a method of rounding counters by ion milling are proposed as such a chamfering method.
The method using ion milling is that a shallow groove is previously formed in the edge or corner of an outline of the slider and the edge or corner is etched by using ion milling method. The edge or corner is etched not only vertically but also horizontally. As a result, the edge or corner is rounded, so that R (a radius of curvature) is as small as about 2 &mgr;m to 3 &mgr;m.
However, the method using ion milling has a problem of redeposition unique to the method. That is, even though ion milling method is used in order to remove chippings, redeposition occurs due to ion milling and redeposit peels off as new particles. Consequently, the method using ion milling has a fatal problem that the particles cause the same problem as the problem caused by chippings.
Moreover, other poli
Fujii Ryuji
Fukuroi Osamu
Oliff & Berridg,e PLC
Renner Craig A.
TDK Corporation
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