Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2001-09-13
2004-04-20
Letscher, George J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06724571
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to magnetic heads for hard disk drives and particularly to magnetic heads having magnetic poles that are formed with a varied nickel-iron alloy composition.
2. Description of the Prior Art
Magnetic heads are generally fabricated utilizing photolithographic, electroplating and thin film deposition techniques to create magnetic shields, magnetic poles and other components on an upper surface of a wafer substrate. In fabricating the magnetic poles utilizing electroplating techniques, a seed layer is first deposited upon a surface of the head, typically utilizing sputter deposition techniques, followed by the fabrication of a patterned photoresist layer, followed by the electroplating of NiFe magnetic pole material upon exposed portions of the seed layer. The magnetic poles are generally composed of a NiFe compound, and it is well known that altering the ratio of Ni and Fe within the pole material will alter the magnetic properties of the pole. For instance, NiFe 80/20 (permalloy) is generally suited best for the main portions of magnetic poles, while NiFe 45/55 is a preferable composition for the portions of the P2 pole tip and of the P1 pole that are disposed adjacent each other with the write gap layer therebetween. Thus, it is known in the prior art to fabricate magnetic poles having separate segments which are composed of NiFe 80/20 and NiFe 45/55.
Where two pole segments composed of NiFe 80/20 and NiFe 45/55 are desired in a magnetic pole, two separate electroplating steps are conducted in which two separate plating baths are utilized, each having a different chemical makeup. Thus, in fabricating such magnetic poles, the first NiFe segment is fabricated in a first electroplating step utilizing the first plating bath, and the second segment is next fabricated in a second electroplating step utilizing the second plating bath.
A need therefore exists for a simplified magnetic pole fabrication method for creating magnetic poles having a varied NiFe ion concentration ratio. The improved magnetic head of the present invention includes magnetic poles having a graduated NiFe ion concentration ratio, in which the poles are fabricated in single electroplating steps, as is described in detail herebelow.
SUMMARY OF THE INVENTION
The hard disk drive of the present invention includes a magnetic head wherein the magnetic poles are formed with a NiFe alloy having a varied composition. The poles are created in a single electroplating process using only a single plating bath, by selecting and altering the electroplating process parameters during the electroplating process. In the preferred embodiment, both the P1 pole and the P2 pole are fabricated with a graduated composition NiFe alloy material. The P1 pole is preferably fabricated such that the initially electroplated lower portions have a relatively low Fe wt. % composition, and the upper P1 pole portions, proximate the write gap layer (which is subsequently fabricated) have a relatively high Fe wt. % composition. The initially electroplated lower portions of the P2 pole (proximate the write gap layer) are fabricated with a relatively high Fe wt. % composition, and the subsequently electroplated upper portions of the P2 pole have a relatively low Fe wt. % composition.
In the NiFe electroplating method of the present invention, the wt. % composition of Ni and Fe in NiFe electroplated material is controlled by selection of the duty cycle of the electroplating current during the electroplating process. Generally, for a particular electroplating bath, where the electroplating current duty cycle is greatest the NiFe electroplated material has a higher Fe wt. %, and where the electroplating current duty cycle is reduced, a lower Fe wt. %.
Therefore, electroplated NiFe components from a single electroplating bath can have differing NiFe concentrations where the electroplating current duty cycle is altered. Particularly, NiFe components can be electroplated with a graduated or changing Ni and Fe concentration by altering the electroplating current duty cycle during the electroplating process. Additionally, the plating rate of the poles can be varied as another way to alter the wt. % composition of Fe in the NiFe plating material during the electroplating process.
It is an advantage of the magnetic head of the present invention that it includes magnetic poles having a graduated Fe concentration.
It is another advantage of the magnetic head of the present invention that it includes magnetic poles in which portions of the magnetic poles that are disposed proximate the write gap layer have higher Fe concentrations than other portions of the magnetic poles.
It is a further advantage of the magnetic head of the present invention that it is easier and less expensive to manufacture in that the graduated Fe concentration magnetic poles are fabricated in a single electroplating process.
It is an advantage of the hard disk drive of the present invention that it includes a magnetic head of the present invention that includes magnetic poles having a graduated Fe concentration.
It is another advantage of the hard disk drive of the present invention that it includes a magnetic head of the present invention that includes magnetic poles in which portions of the magnetic poles that are disposed proximate the write gap layer have higher Fe concentrations than other portions of the magnetic poles.
It is a further advantage of the hard disk drive of the present invention that it includes a magnetic head of the present invention that is easier and less expensive to manufacture in that the graduated Fe concentration magnetic poles are fabricated in a single electroplating process.
These and other features and advantages of the present invention will no doubt become apparent to those skilled in the art upon reading the following detailed description which makes reference to the several figures of the drawings.
REFERENCES:
patent: 4869971 (1989-09-01), Nee et al.
patent: 5570251 (1996-10-01), Shinoura et al.
patent: 5751528 (1998-05-01), Nepela et al.
patent: 5932082 (1999-08-01), Harris et al.
patent: 6025978 (2000-02-01), Hoshi et al.
Dinan Thomas Edward
Robertson Neil Leslie
Tam Alan Jun-Yuan
Guillot Robert O.
International Business Machines - Corporation
IPLO -Intellectual Property Law Offices
Letscher George J.
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