DE1171955B - Method of manufacturing a magnetic head - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school KL: H 03 k

German KL: 21 al - 37/20

Number: 1171 955

File number: N 21504IX c / 21 al

Filing date: April 27, 1962

Opening day: June 11, 1964

The invention relates to a method for producing a magnetic head which is composed of at least two parts which consist of sintered, oxydischemi ferromagnetic material with a cubic crystal structure. Such a material is known under the name »Ferroxcube«. It should be noted here that the invention can also be used to produce mechanical oscillators based on magnetostriction.

In the manufacture of magnetic heads, at least two parts of the mentioned material put together with a small space in between. It is often desirable to keep the gap as small as possible and in particular to determine the gap length within extremely narrow limits and to be reproducible to train.

The mentioned parts were thus far with each other connected that a metal foil or glass is arranged between the parts and this foil or the glass was heated to a relatively high temperature to establish the bond. This The method has several disadvantages; the thickness of the film often exceeds the desired value, and the high temperature to which the film or glass must be heated can affect the magnetic Properties of the parts have a detrimental effect.

The connection cannot be made by a common process with metals such as copper, silver, and gold will. These metals do not wet Ferroxcube and do not adhere to this material. Consequently can use a small gap length (distance between the slit diaphragms) with very low tolerances of the metals mentioned cannot be obtained. In addition, since it is not desirable to keep the temperature at the Choose the connection of the parts so high that thin foils made of zirconium and titanium can be used, to establish the connection, there has been no practical solution for this task up to now.

According to the invention there is a method of manufacturing a magnetic head of the aforementioned type, characterized in that the surfaces which after After assembling, form the delimitation of the effective gap, initially with a very thin one Layer made of a metal from the group consisting of titanium, vanadium, chromium, zirconium, aluminum and magnesium are provided, whereupon a thicker foil made of copper, silver, Gold, nickel or indium is attached, after which the parts are joined by pressure and / or heating get connected. It has been found that the former metals are good at the ferromagnetic material Method of manufacturing a magnetic head

Applicant:

N.V. Philips' Gloeilampenfabrieken, Eindhoven

(Netherlands)

^xo representative:

Dr. rer. nat. P. Roßbach, patent attorney,
Hamburg 1, Mönckebergstr. 7th

Named as inventor:

Robert Lewis Bronner, Irvington, NY,. . . ;.
Ray Collier Hughes, Ardsley, NY (V. St. A.)

Claimed priority: ^[

V. St. v. America May 1, 1961 (106 906) -

wet and adhere to it with great strength; It is also possible to establish a firm connection with the metals of the second group by cold welding or by heating to a relatively low temperature. The temperature at which the connections can be made can be lower than 400 ° C, and this temperature is not harmful to the ferromagnetic material. It should be noted here that it is known to provide two ceramic parts to be connected to one another with the interposition of a metal piece with a thin metal layer and to connect them to one another by pressure or heating. These ⁵ ceramic parts do not consist of a sintered, oxidic, ferromagnetic material with a cubic crystal structure. This material cannot be exposed to very high temperatures without having to accept a considerable loss of magnetic properties, and furthermore only a few metals are able to wet this material well and adhere to it. It should also be noted that the required gap length is nowadays often extremely small.

The invention now relates to a particular choice of metals used, which have good adhesion with two parts made of Ferroxcube. It plays a significant role that not just one good adhesion must be achieved, but that too

409 599/139

only relatively low temperatures can be used. Furthermore, the adhesion between the applied Layers can also be achieved with other metals in a simple manner.

So an existing two-part ceramic support body is known, the two parts of which by a Metal ring are connected to each other. The ceramic parts are metallized and the ring is soldered on. The temperatures used and the accuracy that can be achieved are practically irrelevant Role. Solder is used for the connection, i. H. an alloy of tin and lead. Such a solder joint is by no means able to absorb the forces that occur when pulling and grinding in the manufacture of a magnetic head according to the invention.

In one embodiment of the invention, the very thin layer is preferably applied by vapor deposition attached in a vacuum to the surfaces to be connected; this procedure enables to obtain the low desired thickness of the layer in a reproducible manner in a simple manner.

An even better connection is obtained if, according to a further embodiment of the invention, preferably also by vapor deposition in a vacuum, on the first layer also very much thin layer of copper, silver, gold, nickel or indium is applied before the foil is inserted and the connection is established.

In a further embodiment of the invention, preferably electrolytically, on the first or on of the second very thin layer first a thicker layer of copper, silver, gold, or nickel Indium attached.

A very good, firm and reproducible connection between the parts is obtained if according to Another feature of the invention, the first very thin layer of aluminum or titanium and the second very thin layer consists of gold or silver, on which layer a thicker layer is made Gold or silver is deposited, the foil being made of indium.

The invention is explained in more detail, for example with reference to the drawing, in which

F i g. 1 represents a magnetic head made of Ferroxcube and

F i g. 2 shows, on a greatly enlarged scale, in section the gap of the magnetic head according to FIG.

The head according to Fig. 1 consists of two head halves 1 and I ₁ which are arranged at such a distance from each other that a gap 3 is formed over the z. B. a tape (not shown) with magnetizable material can slide on the surface. Coils 4 of copper wire are placed around the head halves, from which an electrical signal is fed or removed. The two head halves are connected to one another in the manner to be described below both via the effective gap 3 and on the lower side at 5.

From Fig. 2 it can be seen that the connection consists of an aluminum layer (shown too strongly to scale) 6, a thicker gold layer 7, a foil 8, again a gold layer 7 and an aluminum layer 6 consists. The surfaces of parts 1 and 2 to be connected are initially by means of a diamond-containing abrasive with a grain size of 14 μ is polished to a high gloss and then purified in distilled water and acetone.

Thereafter, the surfaces are heated in a vessel with a vacuum of about 10 ~ ⁴ to 10 ~ ⁵ mm Hg to about 250 ° C. In this state, always in the vessel, aluminum and then gold are vaporized onto the surfaces using a heated tungsten filament. The total weight of the vapor-deposited material consisted in a certain case of 5% aluminum and 95% gold, and the total thickness of layer 6 was no greater than 800 A. In particular, 3.1 mg aluminum and 59.1 mg were used Gold, whereby an aluminum skin with a thickness of 91.5 Å and a gold skin of 246 Å were obtained. Then, after cooling, the head halves are removed from the vessel, and a gold layer 7, which has a thickness of 13 μ, is electrolytically deposited on the surfaces. Other metals such as nickel, copper, silver or indium are also suitable for this layer.

A thin film 8 of indium is then attached between the surfaces to be connected, after which the whole is reinserted into the vacuum vessel, where the halves are clamped to a temperature just above the melting point of indium of 156 ° C in a vacuum of about 10 ~ ³ mm Hg. After the indium has become liquid, the parts are kept at the temperature mentioned for about 2 minutes and then cooled. It was found that an excellent strong bond was obtained.

Titanium can be used instead of aluminum; in this case, 25 mg titanium and 60 mg gold Skin thicknesses of 106 A and 247 A were obtained. When using aluminum and silver, these were Values of 15 mg aluminum and 35 mg silver and the skin thicknesses were 441 A and 268 A.

After inserting the indium foil, the connection can also be produced by cold welding be, d. H. by simply connecting the parts by pressure without applying an elevated temperature will.

Claims (7)

Patent claims: 1. A method of manufacturing a magnetic head composed of at least two parts which consist of sintered, oxidic, ferromagnetic material with a cubic crystal structure, characterized in that, that the surfaces that form the boundary of the effective gap after assembly, initially with a very thin one Layer made of a metal from the group consisting of titanium, vanadium, chromium, zirconium, aluminum and magnesium be provided, whereupon a thicker film is made between these surfaces treated in this way Copper, silver, gold, nickel or indium is attached, whereupon the parts by pressure and / or heating. 2. The method according to claim 1, characterized in that the very thin layer on the Areas is attached by vapor deposition in a vacuum. 3. The method according to claim 1 and / or 2, characterized in that on each very thin First layer an almost equally thin layer of copper, silver, gold, nickel or indium is attached. 4. The method according to claim 3, characterized in that that the second, very thin layer is also attached by evaporation in a vacuum. 5. The method according to claim 1, 2, 3 and / or 4, characterized in that on each very thin, first or second layer, first a second or third thicker layer Copper, silver, gold, nickel or indium is attached. 6. The method according to claim 5, characterized in that the thicker layer is electrolytic being knocked down. 7. The method according to claim 5 and / or 6, characterized in that the very thin layer on each surface made of aluminum or titanium and the second very thin layer of gold or Silver consists, upon which a thicker layer of gold or silver is deposited on this layer where the foil consists of indium. Considered publications:
German patent specifications No. 727 325, 723 236. 1 sheet of drawings 409 599/139 6.64 © Bundesdruckerei Berlin