Dynamic magnetic information storage or retrieval – Head – Coil
Reexamination Certificate
1999-07-28
2001-05-01
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Coil
Reexamination Certificate
active
06226147
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thin-film magnetic head with an inductive transducer element for magnetically recording information into a magnetic medium such as a hard disk or a floppy disk, and to a manufacturing method of the thin-film magnetic head.
DESCRIPTION OF THE RELATED ART
Two thin-film magnetic pole layers and a thin-film coil conductor basically constitute an inductive transducer element of such thin-film magnetic head. ABS (Air Bearing Surface) side ends of the respective magnetic pole layers are opposed with each other via a magnetic gap layer and rear portions of the magnetic pole layers are in contact with each other to form a magnetic yoke. The coil conductor is wound around the yoke.
The conventional coil conductors used in such inductive transducer element have been fabricated to have a smooth profile of straight line parts or of straight line parts and partially curved parts in cross section as shown in FIG.
1
.
In case that the coil conductor has such smooth surface, the higher frequency range of the write current, the larger resistance value of the coil conductor due to the skin effect. Larger resistance value of the coil conductor causes not only high heating value and high power consumption but also difficulty in designing and in fabricating a head amplifier. Recently, the write current frequency of the thin-film magnetic head has been requested to more heighten in order to realize higher density magnetic recording. Thus, increase of the resistance value of the coil conductor due to the skin effect has become serious problem.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a thin-film magnetic head and a manufacturing method of the head that can adapt to high-density recording and has a coil conductor with a lower electrical resistance.
Another object of the present invention is to provide a manufacturing method of a thin-film magnetic head that can form a coil conductor with a lower electrical resistance without introducing any additional process.
According to the present invention, a thin-film magnetic head includes a thin-film magnetic circuit that contains a coil conductor with at least one surface. The coil conductor includes a plurality of grooves for reducing electrical resistance of the coil conductor due to skin effect. The grooves are formed on the at least one surface of the coil conductor to run along axis of the coil conductor.
Since a plurality of grooves for reducing electrical resistance of the coil conductor due to skin effect are formed on the surface of the coil conductor to run along axis of the coil conductor, namely along the direction of write current flowing, increasing in resistance due to the skin effect can be suppressed even if the write current frequency more heightens. As a result, the magnetic head can be prevented from heating and high power consumption. In addition, thanks to very low resistance value of the coil conductor, design and fabrication of a head amplifier become very easy.
It is preferred that the coil conductor has side faces, and that the plurality of grooves for reducing electrical resistance due to the skin effect are formed on the side faces.
It is also preferred that the plurality of grooves for reducing electrical resistance due to the skin effect are many grooves with many projections and depressions.
The plurality of grooves for reducing electrical resistance due to the skin effect may have pitches of about 0.05-0.2 &mgr;m, and/or may have a depth of about 0.01-0.1 &mgr;m.
According to the present invention, furthermore, a manufacturing method of a thin-film magnetic head with a thin-film magnetic circuit which contains a coil conductor, includes a step of forming a resist layer, a step of exposing the formed resist layer by applying a monochromatic light via a mask with a predetermined pattern, a step of developing the exposed resist layer without performing a post exposure baking (PEB) process, and a step of plating the coil conductor by using the developed resist layer.
Also, a manufacturing method of a thin-film magnetic head according to the present invention has a step of forming a lower magnetic pole layer, a step of depositing a magnetic gap layer on the lower magnetic pole layer, a step of forming a coil conductor with at least one surface above the magnetic gap layer, and a step of forming an upper magnetic pole layer above the magnetic gap layer. The coil conductor forming step includes a step of forming a low resistance layer on the magnetic gap layer, a step of forming a resist layer on the low resistance layer, a step of exposing the formed resist layer by applying a monochromatic light via a mask with a predetermined pattern, a step of developing the exposed resist layer without performing a post exposure baking (PEB) process, a step of plating the coil conductor by using the developed resist layer, and a step of, thereafter, removing the resist layer.
The resist layer is exposed by a monochrome light and then developed without performing the PEB process. Thus, a plurality of grooves with many projections and depressions are formed on inner walls of resist trenches of the resist layer. Then, by executing frame plating using the resist layer, the coil conductor is formed with both side faces having the many grooves with many projections and depressions along its axis. Since no PEB process is needed, a more simple manufacturing process can provide the coil conductor with a lower resistance.
It is preferred that the exposing step includes a step of exposing the formed resist layer by applying a monochromatic light via a mask with a predetermined pattern to make resist trenches with a plurality of grooves on inner walls of the resist trenches.
It is also preferred that the plurality of grooves are many grooves with many projections and depressions
The plurality of grooves may have pitches of about 0.05-0.2 &mgr;m, and/or may have a depth of about 0.01-0.1 &mgr;m.
REFERENCES:
patent: 4684438 (1987-08-01), Lazzari
patent: 5059278 (1991-10-01), Cohen et al.
patent: 5065270 (1991-11-01), Koyanagi et al.
patent: 5734534 (1998-03-01), Yamamoto et al.
patent: 6066246 (2000-05-01), Richards et al.
patent: 51-148414 (1976-12-01), None
Arent Fox Kintner & Plotkin & Kahn, PLLC.
Evans Jefferson
TDK Corporation
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