Stock material or miscellaneous articles – Structurally defined web or sheet – Continuous and nonuniform or irregular surface on layer or...
Reexamination Certificate
2000-06-22
2003-10-28
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Structurally defined web or sheet
Continuous and nonuniform or irregular surface on layer or...
C428S680000, C428S681000, C428S692100, C428S702000, C428S704000, C360S110000
Reexamination Certificate
active
06638596
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a soft magnetic film used as, for example, a core layer of a thin film magnetic head. More particularly, the present invention relates to a soft magnetic film having soft magnetic characteristics of, in particular, a high resistivity &rgr;, a low coercive force Hc and a high saturation magnetic flux density Ms, to a method of manufacturing the soft magnetic film, and to a thin film magnetic head using the soft magnetic film.
2. Description of the Related Art
A magnetic head mounted on, for example, a hard disc and the like has a thin film magnetic head disposed at the extreme end of a gimbal, and the thin film magnetic film is composed of a writing inductive head and a reading MR head.
The inductive head is ordinarily composed of a lower core layer formed of a magnetic material, an upper core layer facing the lower core layer through a non-magnetic gap layer, and a coil layer for inducing a recording magnetic field to both the layers.
The upper core layer and the lower core layer have been formed of an existing magnetic material such as a Ni—Fe alloy film (Permalloy) and the like. The Permalloy has a high permeability and a relatively high saturation magnetic flux density Ms.
However, when the recording frequency and recording density increase the Permalloy which forms the lower core layer and the upper core layer generates an eddy current because it has a low resistivity &rgr;. A thermal loss is liable to be caused by the eddy current.
SUMMARY OF THE INVENTION
An object of the present invention for solving the above problem is to provide a soft magnetic film which improves the resistivity &rgr; while maintaining the coercive force Hc and a saturation magnetic flux density Ms in a suitable state by adding an element X (X to the Ni—Fe alloy is one or more the group of elements selected from O (oxygen), C (carbon), N (nitrogen), and S (sulfur)) further objects of the present invention are, to provide a method of manufacturing the soft magnetic film, and to provide a thin film magnetic head capable of coping with an increase in the recording density and an increase in the recording frequency by using the soft magnetic film in core layers.
A soft magnetic film of the present invention contains at least Ni, Fe and an element X (X is one or more kinds of elements selected from O, C, N, and S) as the competition thereof, the average grain size of the soft magnetic film is 80 Å or less, and an amount of Fe is 30 percent by mass or more.
It is preferable that the average grain size be within the range of 60 Å or more to 80 Å or less.
It is preferable in the present invention that O, C, and S be contained as the composition of the soft magnetic film.
In the above case, it is preferable that the composition ratio of O+C+S, which is obtained by adding the composition ratios of O, C, and S, be 0.60 percent by mass or more to 5.00 percent by mass or less.
In the range of the above numerical values, it is preferable that the composition ratio of O is 0.40 percent by mass or more to 3.70 percent by mass or less.
It is preferable that the composition ratio of C is 0.11 percent by mass or more to 0.90 percent by mass or less.
Further, it is preferable that the composition ratio of S is 0.05 percent by mass or more to 0.43 percent by mass or less.
In the present invention, the resistivity &rgr; of the soft magnetic film can be made to 60 &mgr;&OHgr;·cm or more to 210 &mgr;&OHgr;·cm or less by restricting the numerical values as described above.
It is more preferable that the composition ratio of O+C+S which is obtained by adding the composition ratios of O, C, and S be 1.16 percent by mass or more to 5.00 percent by mass or less.
Within the range of above numerical values, it is preferable that the composition ratio of O be 0.87 percent by mass or more to 3.70 percent by mass or less.
It is preferable that the composition ratio of C be 0.21 percent by mass or more to 0.90 percent by mass or less.
Further, it is preferable that the composition ratio of S be 0.10 percent by mass or more to 0.43 percent by mass or less.
In the present invention, the resistivity &rgr; of the soft magnetic film can be made to 80 &mgr;&OHgr;·cm or more to 210 &mgr;&OHgr;·cm or less by restricting the numerical values as described above.
In the present invention, it is more preferable that the composition ratio of O+C+S which is obtained by adding the composition ratios of O, C, and S be 1.73 percent by mass or more to 5.00 percent by mass or less.
In the range of above numerical values, it is preferable that the composition ratio of O be 1.30 percent by mass or more to 3.70 percent by mass or less.
It is preferable that the composition ratio of C be 0.32 percent by mass or more to 0.90 percent by mass or less.
Further, it is preferable that the composition ratio of S is 0.15 percent by mass or more to 0.43 percent by mass or less.
In the present invention, the resistivity &rgr; of the soft magnetic film can be made to 100 &mgr;&OHgr;·cm or more to 210 &mgr;&OHgr;·cm or less by restricting the numerical values as described above.
It is preferable in the present invention that the average roughness (Ra) of the centerline of the film surface of the soft magnetic film be 140 Å or less. With this arrangement, the coercive force Hc of the soft magnetic film can be made to 118.5 A/m or less.
In the present invention, it is more preferable that the average roughness (Ra) of the centerline of the film surface of the soft magnetic film be 120 Å or less. With this arrangement, the coercive force Hc of the soft magnetic film can be made to 79 A/m or less.
In the present invention, it is furthermore preferable that the average roughness (Ra) of the centerline of the film surface of the soft magnetic film be 50 Å or less. With this arrangement, the coercive force Hc of the soft magnetic film can be made to 39.5 A/m or less.
In the present invention, the saturation magnetic flux density Ms of the soft magnetic film can be made to 1.0 T or more.
It is preferable that the soft magnetic film be formed by plating.
In the present invention, it is preferable that the soft magnetic film be formed in a plating bath containing Fe ions and Ni ions to which amino organic materials are added and that the soft magnetic film contain at least Fe, Ni and the element X, which is at least one element element selected from the group of O, C, N, and S.
Further, it is preferable in the present invention that saccharin be added to the plating bath. The addition of the saccharin increases particularly the multiplier effect of the saccharin and the amino organic materials, whereby the resistivity &rgr; can be increased because the non-metal element X such as O, C, N, S and the like is contained in the soft magnetic film. Further, it is also possible to reduce the stress of the soft magnetic film formed by the plating through the addition of the saccharin.
In the present invention, it is contemplated that SO
2
contained in the saccharin enters the composition of the soft magnetic film by the addition thereof in the plating bath as described above so that S can be contained in the soft magnetic film.
In the present invention, it is preferable that the pH (index for the hydrogen ion concentration) of the plating bath be kept to 1.8 or less. The pH of the plating bath is more preferably kept to 1.7 or less and furthermore preferably to 1.5 or less.
Further, in the present invention, it is preferable that the temperature of the plating bath be kept within the range of from 20° C. to 28° C.
In the present invention, it is preferable that the amino organic material is at least one or material selected from the group of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), alanine (Ala) and glutamic acid (Glu).
In the present invention, when the element X wherein at least one X is elements selected from the group of O, C, N, and S is contained in the soft magnetic film composed of a Ni—F
Gotoh Mitsuhiro
Kanada Yoshihiro
Kawasaki Mitsuo
Yazawa Hisayuki
Alps Electric Co. ,Ltd.
Bernatz Kevin
Brinks Hofer Gilson & Lione
Thibodeau Paul
LandOfFree
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