Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-07-05
2002-09-03
Cao, Allen (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06445551
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
This invention relates to a bar-shaped head aggregation, a thin film magnetic head, a magnetic head device and a magnetic disk driving device
2) Related Art Statement
In manufacturing of a thin film magnetic head, thin film elements are formed on a wafer, and thereafter, the wafer is cut out to form bar-shaped head aggregations. Each bar-shaped head has aligned plural magnetic head elements. The bar-shaped head aggregation is processed to have its required geometrical shape on its medium opposing surface, and is lapping-processed. Then, it is cut out to each thin film magnetic head element to obtain thin film magnetic heads.
In a bar-shaped head aggregation or a thin film magnetic head which employs, as a reading element, a magnetic resistive effective element such as a magnetic anisotropic resistive effective element, a giant magnetic resistive effective element having a spin valve film or a perovskite type magnetic substance or a ferromagnetic tunnel junction effective element, the magnetic resistive effective element and its leading conductive films are embedded in an insulating film made of alumina, etc. Then, a first and a second shielding films are provided on and under the insulating film, respectively.
In the above bar-shaped head aggregation or thin film magnetic head, if the insulating film, which is located between the leading conductive film and either the first or the second shielding films, is degraded or brought down in its insulation, it may have larger electric noises or less electromagnetic conversion characteristics.
For distinguishing defective thin film magnetic head elements or thin film magnetic heads, such a thin film magnetic head or a bar-shaped head aggregation is required to be examined in its electrical insulation. In a conventional examination for the electrical insulation, the bar-shaped head aggregation and the thin film magnetic head are examined by contacting a probe to the end surface of the first or second shielding film on an air bearing surface of a slider and the terminal conductor of the leading conductive film on the end surface of the slider in the air outflow side.
However, since the shielding film is extremely thin, it is very difficult to contact the probe to the end surface of the shielding film.
Moreover, it is not easy to determine and position in the examination direction two different surfaces of the minute thin film magnetic head element or the thin film magnetic head. Then, it is extremely difficult to contact the probe to the two surface after the positioning.
Since the exposed end surface to the air bearing surface of the shielding film is located near the exposed end surface thereto of the magnetic resistive effective element, the probe to be contacted to the exposed end surface of the shielding film may be contacted to the exposed end of the magnetic resistive effective element by mistake, so that the magnetic resistive effective element may be damaged.
Moreover, the air bearing surface which is required to have a highly smooth surface of submicron-order or below roughness may have scratches by the probe, so that the floating performance of the thin film magnetic head element or the thin film magnetic head may be deteriorated.
Kokai Publication Kokai Hei 8-293018 (JP A 8-293018) discloses that during a wafer processing, the leading conductive film and the shielding film are kept to be electrically connected, and after the wafer processing, they are shut down electrically.
However, this document discloses only to prevent the dielectric degradation and the dielectric destruction of the insulating film during the wafer processing, and even in the disclosed technique, the above examination means is required to examine the electrical insulation of the insulating film between the shielding films in the thin film magnetic head and the bar-shaped head aggregation.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a bar-shaped head aggregation, a thin film magnetic head, a magnetic head device with the thin film magnetic head and a magnetic disk driving device in which an electrical insulation of an insulating film, between shielding films, with an embedded magnetoresistive effective element film can be easily examined.
It is another object of the present invention to provide a bar-shaped head aggregation, a thin film magnetic head, a magnetic head device with the thin film magnetic head and a magnetic disk driving device in which shielding films, a magnetoresistive effective element and an air bearing surface can not be damaged in the electrical insulation measurement for the insulating film, between the shielding films, with the embedded magnetoresistive effective element.
It is further object of the present invention to provide a bar-shaped head aggregation, a thin film magnetic head, a magnetic head device with the thin film magnetic head and a magnetic disk driving device in which an insulating film is prevented from being electrically damaged in processes except the electrical insulation measurement thereof.
It is still further object of the present invention to provide a bar-shaped head aggregation, a thin film magnetic head, a magnetic head device with the thin film magnetic head and a magnetic disk driving device in which a means to prevent the electrical damage for an insulating film can be easily removed in the electrical insulation measurement thereof.
For achieving the above objects, in the bar-shaped head aggregation of the present invention with an aligned plural thin film magnetic head elements, each thin film magnetic head element has at least one electromagnetic conversion element.
The electromagnetic conversion element includes a first shielding film, a first insulating film, a magnetoresistive effective element, a first leading conductor film, a second leading conductor film, a second insulating film, a second shielding film, a first terminal conductor for the first leading conductor film, a second terminal conductor for the second leading conductor film and a terminal conductor for measurement.
The first insulating film is provided on the first shielding film. The magnetoresistive effective element is provided on the first insulating film. The first leading conductor film is formed on the first insulating film and connected to one end of the magnetoresistive effective element. The second leading conductor film is provided on the first insulating film and connected to the other end of the magnetoresistive effective element.
The first terminal conductor is connected to the first leading conductor film and exposed to a different surface of a slider from a medium opposing surface thereof. The second terminal conductor is connected to the second leading conductor film and exposed to a different surface of the slider from the medium opposing surface thereof.
The second insulating film covers the first and the second leading conductor films and the magnetoresistive effective element. The second shielding film is provided on the second insulating film.
The terminal conductor for measurement is conductively connected to at least one of the first and the second shielding films and is exposed to a different surface of the slider from the medium opposing surface thereof.
As mentioned above, since the magnetoresistive effective element, the first and second leading conductor films are provided on the insulating film formed on the first shielding film, they are shielded by and electrically insulated from the first shielding film.
Since the first and second leading conductor films and the magnetoresistive effective element are covered with the second insulating film under the second shielding film, they are shielded by and electrically insulated from the second shielding film.
The measuring terminal conductor is conductively connected to at least one of the first and the second shielding films. That is, the measuring terminal conductor is conductively connected to only either or both of the first and the second shielding film. In the above bar-
Asatani Takashi
Kimura Fujimi
Sato Jun-ichi
Cao Allen
Nguyen Dzung C.
Oliff & Berridg,e PLC
TDK Corporation
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