Metal working – Method of mechanical manufacture – Electrical device making
Patent
1990-08-22
1992-06-23
Hall, Carl E.
Metal working
Method of mechanical manufacture
Electrical device making
360121, 360125, G11B 542
Patent
active
051231565
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method for the production of a read-write magnetic head and particularly to a magnetic head produced by a thin-film technique or, more precisely, thin-film planar heads.
DISCUSSION OF BACKGROUND
A planar type magnetic head possessing magnetic poles produced by a thin-film technique comprises, as is represented in FIG. 1, a magnetic circuit T1 in ferrite, for example, possessing a face T2 carrying two thin-film magnetic poles T3 and T4, separated by an air gap T5. Coils T6 and T7 are wound around the magnetic circuit T1, enabling a magnetic flux to be induced. However, such a magnetic head shows large magnetic losses which reduce the efficiency of the magnetic head. By way of example, the leakages of magnetic field lines have been drawn in FIG. 1. These large leakages produce as a consequence a loss of signal. The invention brings a solution to this problem and thus enables the magnetic losses to be reduced.
SUMMARY OF THE INVENTION
The invention relates to a method for the production of a read-write magnetic head, characterized in that it comprises the following steps:
(a) the production in a substrate made of non-magnetic material, from a first face of the substrate, of a groove possessing two side walls and a bottom;
(b) the production in the groove of a layer of a material with good magnetic permeability covering the two side walls and the bottom of the groove;
(c) the deposition of a non-magnetic material in the groove;
(d) the machining of a second face of the substrate opposite to the first face so as to reach the non-magnetic material located in the groove and to create an air gap between the magnetic materials located on the two side walls;
(e) the bonding of a part carrying a layer of a magnetic material onto the first face of the substrate in such a way that this layer of magnetic material magnetically couples the layers of magnetic material located on the two side walls of the groove.
The invention also relates to a magnetic head produced by the preceding method, characterized in that it comprises:
a substrate of non-magnetic material possessing a slit which opens towards an upper face of this part, this slit being bounded by two side walls and a bottom;
a layer of a material with high magnetic permeability covering the two side walls and the bottom and flush with the upper face of the substrate;
a non-magnetic material situated between the layers of the high magnetic permeability material covering the sides, this non-magnetic material being flush with the upper face of the substrate;
at least one coil passing through the slit 11 of the substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
The different objects and characteristics of the invention will appear more clearly in the description which will follow, given by way of example by referring to the appended figures which represents:
FIG. 1, a magnetic head known in the technique and already described previously;
FIGS. 2 to 11, different steps in the method of producing a magnetic head in accordance with the invention;
FIG. 12, an example of the embodiment of a thin-film magnetic head according to the invention;
FIG. 13, a variant of the embodiment of a thin-film magnetic head according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
By making reference to FIGS. 2 to 11, an example of the embodiment of a method of production according to the invention will first be described.
In the course of a first step, represented in FIGS. 2 and 3, grooves such as 11 are cut into a substrate of non-magnetic material This groove has, for example, a triangular shape bounded, from the surface 10 of the substrate, by two side walls 12 and 13 and possesses a bottom 14.
By ay of example, provision will, be made for grooves with a depth of about 500 micrometers and a width from 500 to 800 micrometers in a thickness of substrate from 5 to 10 mm.
In the course of a second step represented in FIG. 4, the face 10 and the sides 12 and 13 of the groove 11 are coated with a layer 2 of a material havi
REFERENCES:
patent: 2647031 (1954-04-01), Buhrendorf
patent: 3000078 (1961-09-01), Emenaker et al.
patent: 3613228 (1971-10-01), Cook
patent: 4412379 (1983-11-01), Lemke et al.
patent: 5016342 (1991-05-01), Pishavoda et al.
IBM Technical Disclosure Bulletin, vol. 11, No. 11, Apr. 1969, Armonk, N.Y., US, p. 1595 J. M. Brownlow et al.: "Batch-Fabricated Magnetic Head".
Coutellier Jean-Marc
Meunier Paul-Louis
"Thomson-CSF"
Hall Carl E.
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