Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
2001-02-21
2003-09-23
Eley, Timothy V. (Department: 3724)
Abrading
Abrading process
Glass or stone abrading
C451S158000, C451S005000, C451S055000, C451S276000, C451S279000, C451S387000
Reexamination Certificate
active
06623336
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head polishing device for polishing an object to be polished where a plurality of magnetic heads are disposed and a magnetic head polishing method, and more particularly to a device for correcting a bend of the workpiece or object to be polished at the time of polishing.
2. Related Background Art
A thin film magnetic head used in a magnetic disk device or the like is made up of parts obtained by machining a bar-shaped ceramics (hereinafter referred to “ceramic bar”) where a large number of element parts made of magnetic thin films and the like, which form an induced magnetic conversion element or a magnetic resistor element (hereinafter referred to as “MR element”) and the like, are formed on a surface in a line. The large number of element parts are formed on a wafer-shaped ceramic substrate at the same time, and the ceramic substrate is cut into a bar shape in one direction, to thereby obtain the above-mentioned ceramic bar.
The large number of element parts are formed on the wafer-shaped ceramic substrate at the same time with the use of a thin film forming and processing technique represented by a semiconductor manufacturing technique. In this process, the respective thin films for magnetic resistance measurement, a magnetic pole, a coil, insulation, and the like, are subjected to film formation, photoresist coating, exposure of a wiring shape, and the like, the removal of the photoresist on a portion to be exposed, a film etching on the portion to be exposed, the removable of the photoresist on an exposing portion, and the like. Thereafter, a protective film is formed on the uppermost portion, and a process of forming the element portion is completed.
In addition, in the next process, a ceramic bar formed with a plurality of element parts is subjected to a polishing process that machines a throat height, an MR height, or the like of each element part to an appropriate value, and other processes. In general, in the magnetic disk device, in order to stabilize the output characteristic from the magnetic head, it is necessary to keep a distance between the magnetic pole portion of the magnetic head and a recording medium surface to a very narrow constant distance. The throat height or the MR height becomes an important parameter that regulates this distance.
In a subsequent process, the ceramic bar is separated into the respective element parts, individually, and the respective element parts constitute one part of the magnetic head for the magnetic disk device. When the magnetic head is used for the magnetic disk device, the ceramic portion becomes a slider that floats due to an air pressure by the rotation of a disk on the magnetic disk, and the element portion becomes a head core that conducts the record and/or reproduction of a magnetic signal of the disk.
The throw height is regulated by a magnetic pole leading portion that conducts the record and reproduction of a magnetic signal in the above head core, and is directed to the length (height) of a portion of two magnetic poles that face each other with a fine gap therebetween. The MR height is directed to the length (height) from an end portion on the side of the surface facing the medium of the MR element to the opposite end portion. In order to enable an appropriate recording and reproduction of the signal, it is needed that the values of the throat height and the MR height are set to given values, and a high precision is required for polishing process in order to obtain the given values.
However, in general, the above ceramic bar has a distortion, a bend or the like due to a stress caused by cutting of the respective element portions from the ceramic substrate or the formation of the element portions, and the like, and it is difficult to obtain the above-mentioned high processing accuracy only by fixing the ceramic bar to conduct the polishing process. For that reason, there has been proposed a device for polishing the magnetic head in the form of a ceramic bar with a high precision as disclosed, for example, in U.S. Pat. No. 5,620,356, instead of the general polishing device. Also, the present applicants have proposed such devices and methods (Japanese Patent Application No. 11-162799, and the like).
A method of polishing the above ceramic bar in fact will be described below.
First, a counter surface to the polished surface of the ceramic bar is stuck on a jig by means of an adhesive or the like, and the surface to be polished of the ceramic bar is pushed toward a polishing surface of a polishing bed or base through the jig, to thereby polish the surface to be polished. The jig is of a beam structure, and a load is given to specific points three to seven on the jig from the outside of the jig, to thereby deform the jig per se. In addition, the beam structure facilitates a portion to which the ceramic bar is stuck to be complicatedly deformed by the above load and also can correct the bend or the like of the ceramic per se by bending the stuck ceramic bar at the same time.
During polishing, the value of the throat height or the like is optically or electrically measured on a given element portion on the ceramic bar fixed by the jig, and a difference between the measured value and a desired value, that is, a polishing amount required at the time of measurement is obtained. The loads at a plurality of points are adjusted on the basis of the required polishing amount at an obtained predetermined element portion and a portion close to the element portion, and a process of conducting polishing while deforming the ceramic bar through the jig is repeated, to thereby fall values of the throat height or the like of all the elements formed in the ceramic bar within a given range.
In the above process, the jig is made into a beam structure in order to make the deformation easy, and an opening portion into which a pin or the like that gives a load is inserted is defined in the beam portion. A load caused by an actuator such as a low frictional cylinder is transmitted to the pin through a transmission part, to thereby deform the entire jig and deform the ceramic bar fixed to a part of the jig, or adjust a load on the respective ceramic bar portions. A specific example of the jig that conducts the effective deformation or the load diffusion on the ceramic bar is disclosed in Japanese Patent Application No. 10-178949 made by the present applicants.
However, as the recording density of the magnetic recording medium is made high, an error range which is allowed to the value of the throat height or the like during the polishing process becomes narrower. In order to comply with this requirement in the above conventional device, it is necessary to give a fine deformation by a ceramic bar holding portion. However, in order to obtain the fine deformation, more points to which the load is applied are disposed, and a device that can give larger loads to those points is required. Taking the size of the actuator having a required stroke, and the like, into consideration, it is difficult to structure an actual device. Also, the jig of the conventional device in which the entire jig is always deformed is naturally improper in deforming the respective parts, independently.
For that reason, the present applicant has proposed a method in which a main load that presses the ceramic bar against the polishing surface is given by about one to three actuators, and pressing forces from a plurality of micro-actuators small in stroke are directly effected on the portion that holds the ceramic bar for fine adjustment. According to this method, the micro-actuator small in stroke, and the like, can be employed by directly effecting the pressing force onto the ceramic bar holding portion, and a problem on a space to which the actuator is attached is eliminated. In addition, a specific portion of the ceramic bar holding portion can be pressed, thereby being capable of more finely correcting the bend of the ceramic bar.
As described above, an error allowed to the mac
Abe Tetsuo
Kouzu Masaki
Ogawa Akio
Sasaki Masahiro
Shindou Hiroshi
Eley Timothy V.
TDK Corporation
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