A first magnetic material film is deposited on a support, a groove is etched in the first magnetic film which is shaped like a figure eight, a double coil is formed and is wound respectively around the two central pole pieces. An insulating material layer is deposited and etched in step form, the step having a side facing the central channel. An magnetic amagnetic film is deposited on the thus etched step, and the film is etched so as to only leave a wall perpendicular to the plane of the films. This is followed by the deposition of a magnetic film and then a protective layer, the assembly being divided off so as to expose two pole pieces separated by an air gap amagnetic gap.
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1. A process for producing a magnetic read-write head, comprising the steps of: depositing a first magnetic material film on a support, etching a groove in said first magnetic film, said groove being shaped like a figure eight with two loops having in common a rectilinear central portion, the magnetic film being preserved within said two loops and forms there two central pole pieces separated by a central channel corresponding to the central portion of the figure eight, filling the groove with an electrically insulating material, etching in the insulating material a notch forming a double groove wound respectively around the two central pole pieces, depositing a conductive coating at the bottom of the double groove and then filling the double groove with a first electrically insulating material, depositing a second insulating material layer on the two central pole pieces and on the first electrically insulating material, etching in said layer a step having a side substantially perpendicular to the surface of the central portion of the figure eight but which is slightly off-center with respect thereto, depositing an amagnetic material film on the thus etched step, anisotropic etching said amagnetic film so as to only leave a wall of said amagnetic film perpendicular to the plane of the films and constituted by that part of the amagnetic film depositing on the side of the step, depositing a second magnetic material film forming a boss covering the wall, depositing a protective coating on said second magnetic material film and covering the boss and cutting the protective coating of the second magnetic material film and the amagnetic wall, along a common horizontal plane substantially parallel to said first magnetic film, pole pieces are separated by an air amagnetic gap.
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The present invention relates to a process for producing a magnetic read and write head and to a head obtained by this process. It is used in magnetic recording equipment and in particular in computer memories.
The magnetic head according to the invention is of the type comprising two pole pieces, a double flat spiral coil surrounding each of the pole pieces and an air gap filled with an amagnetic material, the latter being flush with the level of the planar surface forming what is called the flight or displacement plane of the head. The magnetic recording support moves relative to the head in front of the air gap and parallel to the displacement plane. During writing, a current flowing in the winding leads to a magnetic field at the air gap, so that information is written into the support. Conversely, magnetic information written on to the moving support induces a field in the pole pieces, i.e. a current in the coil and a voltage at the terminals thereof, which constitutes a measuring signal. As the magnetic field involved in these reading and writing operations is parallel to the recording support, the term horizontal magnetic recording is sometimes used.
For example, such a head is described in Japanese Pat. No. 56 83823 filed by FIJITSU K.K. and entitled "Production of horizontal thin film magnetic head", whose abstract was published in Patent Abstracts of Japan, vol. 5, no. 150 (P-81) (822) of 22.9.1981.
The process for producing such a head comprises the end to end bonding of two thin magnetic pieces on a substrate, said magnetic pieces being separated by a nonmagnetic layer defining the air gap. This assembly is then machined to reduce the height of the air gap. Separately a support is formed comprising a double winding surrounding the two pole pieces. These two subassemblies are then bonded together.
Such a process suffers from numerous disadvantages. Firstly, it requires sensitive fitting of small parts, which makes it relatively incompatible with industrial, automated processes. The read and write pole pieces have on the one hand a significant width, which is prejudicial to the efficiency of the head, and on the other hand is of a relatively non-reproducible nature, which leads to performance variations. Finally, it can induce interference fields in the recording layer.
The present invention relates to a process for producing a magnetic head obviating the aforementioned disadvantages. As operations based on thin film technology are used, the process is suitable for automation. The width of the read and write pole pieces defined by the thickness of a thin film, so that said thickness is limited and perfectly reproducible. Moreover, the conductor winding is inserted between two magnetic films and is consequently completely shielded.
The present invention more specifically relates to a process for producing a magnetic read-write head, wherein it comprises the operations of depositing a first magnetic material film on a support, etching a groove in said first magnetic film, said groove being shaped like a figure of eight with two loops having in common a rectilinear central portion, the magnetic film being preserved within said two loops and forms there two central pole pieces separated by a central channel corresponding to the central part of the figure of eight, filling the groove with an electrically insulating material, etching in the insulating material a notch forming a double groove wound respectively around the two central pole pieces, depositing a conductive coating at the bottom of the double groove and filling the double groove with an electrically insulating material, depositing an insulating material layer, etching in said layer a step having a side facing the central channel, but which is slightly offcentred with respect thereto, depositing an amagnetic material film on the thus etched step, etching said amagnetic film so as to only leave a wall perpendicular to the plane of the films and constituted by that part of the amagnetic film deposited on the side of the step depositing a second magnetic material film forming a boss covering the wall, depositing a protective coating exactly following the shape of the boss and cutting the protective coating of the boss and the amagnetic wall, so that two pole pieces separated by an air amagnetic gap between the two pole pieces 36a, 36b. The magnetic film 36 has a thickness between 0.2 and 1.5 μm, i.e. it is very thin. The same applies with regards to pole pieces 36a, 36b, whose width is of the same order of magnitude as said thickness. This leads to the high efficiency of the magnetic head according to the invention.
FIG. 9 shows the head which is finally obtained. The arrows representing the flux or flow lines on writing in a magnetic support 42 moving in front of the flight or displacement plane 41 constituted by what is left of the coating 38.
It is pointed out that the two lateral portions of the coil are magnetically shielded by the two films 24 and 36, so that they produce no leakage field towards the recording coating 42.
Finally, FIG. 10 shows an exploded view of the head observed in front of its flight or displacement plane. Only the ends of the two read and write pole pieces 36a, 36b separated by wall 34a are flush with the level of the flight plane.
| Patent | Priority | Assignee | Title |
| 5155643, | Oct 30 1990 | MEI, INC | Unshielded horizontal magnetoresistive head and method of fabricating same |
| 5378885, | Oct 29 1991 | MEI, INC | Unshielded magnetoresistive head with multiple pairs of sensing elements |
| 5504643, | Sep 06 1993 | PLANHEAD SILMAG PHS | Magnetic read/write head having a writing-compensated magnetoresistant element |
| 8427780, | Jan 23 2009 | International Business Machines Corporation | Planar magnetic writer having offset portions |
| Patent | Priority | Assignee | Title |
| 4025411, | Oct 25 1974 | Hitachi, Ltd. | Fabricating semiconductor device utilizing a physical ion etching process |
| 4256514, | Nov 03 1978 | International Business Machines Corporation | Method for forming a narrow dimensioned region on a body |
| JP5683823, |
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