Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1999-09-07
2001-11-13
Ometz, David L. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06317291
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film magnetic head having at least an induction-type magnetic transducer and a method of manufacturing the thin-film magnetic head.
2. Description of the Related Art
Thin-film magnetic heads have been widely used in hard disk drives used for computers and so on. Composite thin-film magnetic heads in particular have been widely used. A composite thin-film magnetic head is made of a layered structure including a recording head having an induction-type magnetic transducer for writing and a reproducing head having a magnetoresistive (MR) element for reading.
An induction-type magnetic transducer has two magnetic layers and a thin-film coil placed between the magnetic layers. The magnetic layers include magnetic pole portions opposed to each other with a gap layer in between. The pole portions are placed on a side of end faces of the magnetic layers facing toward a recording medium. The magnetic layers are magnetically coupled to each other on the other side.
With an increase in recording density of a hard disk drive used for computers and so on, the maximum frequency of data recorded or reproduced through the use of a thin-film magnetic head has reached a frequency as high as 100 MHz or above. In the case of an extremely high-speed hard disk drive, in particular, the maximum frequency of data to write has reached the order of 200 MHz. If the frequency of data to write increases, eddy current loss increases in the magnetic layers of an induction-type magnetic transducer. Accordingly, the following problems of reductions in properties have arisen: a reduction in intensity of a write magnetic field generated from the pole portions opposed to each other with the gap layer in between; an increase in delay between a write current (a current responsive to data to write) supplied to the coil and generation of a write magnetic field; and a decrease in gradient of rise of a write magnetic field with respect to time.
In order to suppress such eddy current loss, measures have been devised in related art, such as reducing a magnetic path length, that is, the length of the magnetic path made up of the magnetic layers between the medium-facing-surface-side end and the other end, or using a magnetic material with a high resistivity for the magnetic layers.
To improve recording density, it is desired that track density is increased. In Japanese Patent Application Laid-open Hei 8-87717 (1996), a thin-film magnetic head is disclosed for increasing track density. In the head an end of an insulating layer on which a thin-film coil is formed is placed at least 3 &mgr;m away from the zero throat height position (the position of the medium-facing-surface-side end of an insulating layer that defines the throat height) toward the rear gap (portions of two magnetic layers in contact with each other). In the head the start point of the thin-film coil may be placed at least 10 &mgr;m away from the zero throat height position. In the invention the throat height is the length (height) between the medium-facing-surface-side end of the pole portion and the other end. The throat height is also the length (height) between the medium facing surface and the medium-facing surface-side end of the insulating layer electrically isolating the thin-film coil.
However, the magnetic path length is not reduced in such a structure. It is therefore difficult to sufficiently increase the intensity of a write magnetic field or the gradient of rise of a write magnetic field with respect to time when the frequency of data to write increases.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a thin-film magnetic head and a method of manufacturing the same for improving performance characteristics thereof in the case where the frequency of data to write is high, in particular.
A thin-film magnetic head of the invention comprises: a medium facing surface that faces toward a recording medium; first and second magnetic layers magnetically coupled to each other and including magnetic pole portions opposed to each other and placed in regions on a side of ends of the magnetic layers facing toward the recording medium, the magnetic layers each being made up of at least one layer; a gap layer provided between the pole portions of the two magnetic layers; and a thin-film coil placed between the magnetic layers, being insulated from the magnetic layers. A distance between the medium facing surface and an outermost end of the coil in a direction parallel to surfaces of the gap layer is greater than a throat height and measures 10 &mgr;m or less.
A method of the invention is provided for manufacturing a thin-film magnetic head comprising: a medium facing surface that faces toward a recording medium; first and second magnetic layers magnetically coupled to each other and including magnetic pole portions opposed to each other and placed in regions on a side of ends of the magnetic layers facing toward the recording medium, the magnetic layers each being made up of at least one layer; a gap layer provided between the pole portions of the two magnetic layers; and a thin-film coil placed between the magnetic layers, being insulated from the magnetic layers. The method includes the steps of: forming the first magnetic layer; forming the gap layer on the first magnetic layer; forming the thin-film coil on the first magnetic layer such that a distance between the medium facing surface and an outermost end of the coil in a direction parallel to surfaces of the gap layer is greater than a throat height and measures 10 &mgr;m or less; and forming the second magnetic layer on the gap layer and the coil.
According to the thin-film magnetic head or the method of manufacturing a thin-film magnetic head of the invention, the distance between the medium facing surface and the outermost end of the coil is 10 &mgr;m or less. As a result, the intensity of a write magnetic field and the gradient of rise of a write magnetic field with respect to time reach optimal values.
According to the head or the method of the invention, it is preferred that the distance between the medium facing surface and the outermost end of the coil in the direction parallel to the surfaces of the gap layer is greater than the throat height and measures 8 &mgr;m or less.
Other and further objects, features and advantages of the invention will appear more fully from the following description.
REFERENCES:
patent: 4713711 (1987-12-01), Jones, Jr. et al.
patent: 5621596 (1997-04-01), Santini
patent: 6101068 (2000-08-01), Ohtomo et al.
patent: 6134080 (2000-10-01), Chang et al.
patent: 6181514 (2001-01-01), Santini et al.
patent: A-3-132910 (1991-06-01), None
patent: A-8-87717 (1996-04-01), None
Iwai Yuzuru
Kudo Yoshihiro
Yamanaka Noboru
Oliff & Berridg,e PLC
Ometz David L.
TDK Corporation
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