FIELD OF THE INVENTION

[0001] The present invention pertains to a method and apparatus for processing slider devices for hard disk drives and the like. More particularly, the present invention pertains to lapping slider air bearing surfaces, especially for GMR type heads.

BACKGROUND TO THE INVENTION

[0002] Hard disk drives are common information storage devices essentially consisting of a series of rotatable disks that are accessed by magnetic reading and writing elements. These data transferring elements, commonly known as transducers, are typically carried by and embedded in a slider body that is held in a close relative position over discrete data tracks formed on a disk to permit a read or write operation to be carried out. In order to properly position the transducer with respect to the disk surface, an air bearing surface (ABS) formed on the slider body experiences a fluid air flow that provides sufficient lift force to “fly” the slider and transducer above the disk data tracks. The high speed rotation of a magnetic disk generates a stream of air flow or wind along its surface in a direction substantially parallel to the tangential velocity of the disk. The air flow cooperates with the ABS of the slider body which enables the slider to fly above the spinning disk. In effect, the suspended slider is physically separated from the disk surface through this self-actuating air bearing. The ABS of a slider is generally configured on the slider surface facing the rotating disk, and greatly influences its ability to fly over the disk under various conditions.

[0003] As shown in FIG. 1 an ABS design known for a common catamaran slider 5 may be formed with a pair of parallel rails 2 and 4 that extend along the outer edges of the slider surface facing the disk. Other ABS configurations including three or more additional rails, with various surface areas and geometries, have also been developed. The two rails 2 and 4 typically run along at least a portion of the slider body length from the leading edge 6 to the trailing edge 8 . The leading edge 6 is defined as the edge of the slider that the rotating disk passes before running the length of the slider 5 towards a trailing edge 8 . As shown, the leading edge 6 may be tapered despite the large undesirable tolerance typically associated with this machining process. The transducer or magnetic element 7 is typically mounted at some location along the trailing edge 8 of the slider as shown in FIG. 1 . The rails 2 and 4 form an air bearing surface on which the slider flies, and provide the necessary lift upon contact with the air flow created by the spinning disk. As the disk rotates, the generated wind or air flow runs along underneath, and in between, the catamaran slider rails 2 and 4 . As the air flow passes beneath the rails 2 and 4 , the air pressure between the rails and the disk increases thereby providing positive pressurization and lift. Catamaran sliders generally create a sufficient amount of lift, or positive load force, to cause the slider to fly at appropriate heights above the rotating disk. In the absence of the rails 2 and 4 , the large surface area of the slider body 5 would produce an excessively large air bearing surface area. In general, as the air bearing surface area increases, the amount of lift created is also increased.

[0004] As-illustrated in FIG. 2, a head gimbal assembly 40 often provides the slider with multiple degrees of freedom such as vertical spacing, or pitch angle and roll angle which describe the flying height of the slider. As shown in FIG. 2, a suspension 74 holds the HGA 40 over the moving disk 76 (having edge 70 ) and moving in the direction indicated by arrow 80 . In operation of the disk drive shown in FIG. 2 , an actuator 72 moves the HGA over various diameters of the disk 76 (e.g., inner diameter (ID), middle diameter (MD) and outer diameter (OD)) over arc 78 .

[0005] Giant Magnetoresistive (GMR) heads are being used more and more for advanced hard disk drive (e.g., capable of storing more than 80 gigabytes of data). GMR heads, which are well-known in the art, include components generally located in the middle of the trailing portion of the slider (not the air bearing surface of the slider). These components are quite susceptible to damage induced by head manufacturing processes, particularly during lapping processes. An example of a lapping operation and a plate used for the operation are shown in U.S. Pat. No. 4,866,886 to Holmstrand. The plate includes an embedded abrasive (e.g., diamond particles) and is spun so as to abrade a surface of the GMR head held in place over the moving plate. An abrasive slurry can be added to the plate to facilitate the abrading process. As known in the art, the lapping plates include “lands” and “grooves.” The lands are at a greater height than the grooves on the lapping plate and come into contact with the slider surface. The grooves become a repository for the abrasive particles (e.g., the particles in the slurry, the particles originally embedded in the lapping plate, etc.). The grooves also become a repository for the material removed from the slider.

[0006] Using lapping plates as described above can cause problems in the manufacture of GMR heads. The relatively large abrasive particles can damage the GMR head portion of the slider. One approach to improving head manufacture is to use smaller particles in the lapping plate. As the abrasive particles become smaller, however, it becomes harder to control lapping plate flatness, texture, roughness and cleanliness to successfully embed diamond abrasive, for example (sometimes referred to as the charging process).

[0007] The texturing process for the lapping plate could have a profound impact on GMR head performance of the slider. The texture of the lapping plate will have an effect on slider properties such as surface finish, pole tip recession (or PTR), smearing (i.e., potentially causing device shorting), and bulk removal rates.

[0008] The Holmstrand reference refers to one such texturing process. In Holmstrand, small cavities in the surface of the lapping plate are created using a glass bead blasting apparatus. Using the texturing process of Holmstrand, the PTR can be controlled to an order of 28 microns. With current sliders, however, the PTR is controlled to less than 0.01 microns. One possible reason for such a high value may be that the cavities serve as reservoirs for abrasive sludge instead of allowing the sludge to leave the surface of the disk (e.g., through centrifugal force of, the spinning lapping plate). Accordingly, this texturing process is not acceptable for current slider manufacturing.

[0009] Another process is where spiral grooves are provided in the surface of the lapping plate. The spiral grooves are formed using a facing machine. The width and spacing of the lands and grooves is referred to as the “pitch” of the lapping plate. After the spiral grooves are formed, the lapping plate is further processed by “deburring” (or shaving), which knocks off high peaks and leaves the lands for diamond charging. One problem with the deburring process is that it typically induces machine related burrs, uneven land to groove ratios, broken edges of the plateau and varying depths of the groove 4 . These, in turn, could directly or indirectly affect the properties of the finished slider. One solution is to finely control the operation and function of the facing machine, though doing so can be an expensive and time-consuming process.

[0010] Yet another process for fabricating a lapping plate includes the use of a diamond-textured ring process. As described in U.S. Pat. No. 4,037,367 to Kruse, the natural flow of grooves facilitates a relative easy removal of sludge unlike that shown in the Holmstrand patent. Though the process in Kruse may improve bulk removal rates and pole tip recession, the roughness of the land area is uneven and excessive plate material debris may be caught in the grooves and be difficult to remove. In such a case it may become harder to charge the land areas with smaller size diamond particles (i.e., ones have a mean diameter of, 1.0 microns). Another disadvantage of this process is that the amount of plate debris increases with increased softness of the plate material, thus limiting this process to hard plate materials.

[0011] In view of the above, there is a need for an improved lapping plate and method of manufacturing such plates the reduces plate debris.

SUMMARY OF THE INVENTION

[0012] According to an embodiment of the present invention, a method and apparatus for manufacturing a lapping plate are provided. In one embodiment, the metal plate is first chemically etched using mask-etch procedure that are known in the silicon chip manufacturing field. The areas of the metal plate that are not etched during this procedure form lands in which diamond charging can be accomplished. The resulting lapping plate may be used with sensitive GMR heads because of the relatively small diamond particles that can be charged into the metal plate and their relatively even distribution across the plate.