CA1235483A

CA1235483A - Magnetic transducer head

Info

Publication number: CA1235483A
Application number: CA000476839A
Authority: CA
Inventors: Tomio Kobayashi; Junichi Saito; Heikichi Sato; Tatsuo Kumura
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1984-03-29
Filing date: 1985-03-19
Publication date: 1988-04-19
Also published as: JPS60205808A; JPH0475563B2; KR850006946A; KR930002392B1

Abstract

ABSTRACT
A magnetic transducer head in which the magnetic core elements of ferromagnetic oxides are sliced obliquely across the junction surface of the core elements, ferromagnetic metal thin films are formed on the resulting inclined surfaces by employing a physical vapor deposition, and the core elements are placed with the respective ferromagnetic metal thin films abutting to each other for defining a magnetic gap therebetween, wherein the improvement consists in that the inclined surfaces with the ferromagnetic metal thin films formed thereon are inclined at a preset angle with the magnetic gap forming surface, in that non-magnetic films having high-hardness are interposed between the ferro-magnetic oxide and the ferromagnetic metal thin films, and in that the ferromagnetic metal thin films and the oxide glass fillers are provided on the tape abutment surface by the intermediary of the non-magnetic film having high-hardness. The provision of the non-magnetic film having high-hardness between the ferromagnetic oxide and the ferro-magnetic metal thin film is effective to inhibit the reaction otherwise occurring between the oxide and the films, while positively preventing the formation of the boundary layer with inferior magnetic properties. Likewise, the provision of the non-magnetic film having high-hardness between the ferro-magnetic metal thin film and the oxide glass is effective to prevent the erosion of the film by the molten glass, while also improving the molten glass fluidity. It should be noted that the non-magnetic films hazing high-hardness may be provided on the interface only between the core elements and the metal thin films or on the interface only between the metal thin films and the oxide glass.

Description

~235~L~3 MAGNETIC TRANSDUCER HEAD
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to a magnetic transducer head and more particularly to a so-called composite type magnetic transducer head in which head portion in the vicinity of the magnetic gap is formed by the ferromagnetic metal thin film or films.

2. Description of the Prior Art With the recent tendency towards increasing the signal recording density on the magnetic tape used for VTRs (video tape recorders), so-called metal magnetic tapes in which powders of ferromagnetic metal such as Fe, Co or No are used as magnetic powders for the recording medium, or so-called metallized tapes in which the ferromagnetic metal material is deposited in vacuum on the base film, are used in increasing numbers. The magnetic material of the magnetic transducer head employed for signal recording and reproduction is required to have a high saturation magnetic flux density By in order to cope with the high coercive force Ha of the recording media described above. With the ferrite material predominantly used as the head material, the saturation magnetic flux density By is rather low, while the Permalloy presents a problem in that it has a lower wear resistance.
With the above described tendency towards increasing ~235~3 the signal recording density, it is more preferred to make use of the narrow track width of the magnetic recording medium and hence the magnetic transducer head is required to have a correspondingly narrow recording track width.
In order to meet such requirements, a composite type magnetic transducer head is known in the art in which the ferromagnetic metal thin film having high saturation flux density is applied on the non-magnetic substrate e.g. of ceramics so as to be used as the recording track portion of the magnetic tape. The magnetic transducer head however presents a high magnetic reluctance because the path of magnetic flux is formed only by the ferromagnetic metal film of a reduced film thickness so that the operating efficiency is correspondingly lowered. In addition, an extremely time consuming operation is involved in the manufacture of the magnetic transducer head because the physical vapor deposit lion with extremely low film-forming speed are necessarily employed for the formation of the ferromagnetic metal thin films.
A composite type magnetic transducer head is also known in the art in which the magnetic core elements are formed of ferromagnetic oxides such as ferrite and the ferromagnetic metal thin films are applied to the magnetic gap forming surface of these core elements. However, the path of magnetic flux and the metal thin film are disposed at right angles with ~23S~83 each other and hence the reproduction output may be lowered due to the resulting eddy current loss. Also a pseudo gap is formed between the ferrite magnetic core and the metal thin film thus detracting from the operational reliability.
Summary of the Invention It is therefore a principal object of the present invention to overcome the above described deficiency of the prior art and to provide a composite type magnetic trays-dicer head consisting of the ferromagnetic oxide and the ferromagnetic metal thin films, which is improved in molten glass fluidity, bonding properties and relaxation in the internal stress, and which is free from deterioration in the ferromagnetic metal thin film or ferromagnetic oxides, crack, breakage, erosion or bubbles in the glass fillers.
With the foregoing object in view, the present invent lion resides in a magnetic transducer head in which the magnetic core elements of ferromagnetic oxides are sliced obliquely across the junction surface of the core elements, ferromagnetic metal thin films are formed on the resulting inclined surfaces by employing a physical vapor deposition, and the core elements are placed with the respective ferry-magnetic metal thin films abutting to each other for defining a magnetic gap there between, wherein the improvement consists in that said inclined surfaces with the ferromagnetic metal thin films formed thereon are inclined a-t a preset ~L2354~3 angle with the magnetic gap forming surface, in that non-magnetic films having high-hardness are interposed between the ferromagnetic oxide and the ferromagnetic metal thin films, and in that said ferromagnetic metal thin films and the oxide glass fillers and provided on the tape abutment surface by the intermediary of the non-magnetic film having high-hardness.
The provision of the non-magnetic film having high-hardness between the ferromagnetic oxide and the ferromagnetic metal thin film is effective to inhibit the reaction otherwise occurring between the oxide and the films, while positively preventing the formation of the boundary layer with inferior magnetic properties.
Likewise, the provision of the non-magnetic film having high-hardness between the ferromagnetic metal thin film and the oxide glass is effective to prevent the erosion of the film by the molten glass, while also improving the molten glass fluidity.
Brief Description of the Drawings Fig. 1 is a perspective view showing an embodiment of the magnetic transducer head according to the present invention.
Fig. 2 is a plan view showing the contact surface thereof with the magnetic tape.
Fig. 3 is a perspective view showing the magnetic ~Z354~3 transcuder head shown in Fig. 1, with the head exploded along the magnetic gap surface.
Fig. 4 is a plan view showing the contact surface with the magnetic tape and especially showing the construction of the non-magnetic film having high-hardness.
Fig. 5 shows in perspective a preferred construction of the magnetic transducer head in which the non-magnetic films having high-hardness are provided only on the interface between the ferromagnetic oxide and the ferry-magnetic metal thin films and Fig. 6 shows in perspective a preferred construction of the magnetic transducer head in which the non-magnetic films having high-hardness are provided only on the interface between the ferromagnetic metal thin films and the oxide glass.
Fig. 7 to 14 are diagrammatic perspective views showing the manufacture process for the magnetic transducer head shown in Fig. l, wherein Fig. 7 shows the step of forming a first series of grooves, Fig. 8 the step of forming the non-magnetic film having high-hardness, Fig. 9 the step of forming the ferromagnetic metal thin film, Fig. 10 the step of forming the non-magnetic film having high-hardness, Fig. if the step of charging molten glass filler and the surface grinding step, Fig. 12 the step of forming a second series of grooves, Fig. 13 the step of forming the winding slot, and Fig. 14 the step of melt bonding or glass bonding.

1~35~3 Fig. 15 is a perspective view showing a second embodiment of the invention.
Fig. 16 to 24 are perspective views showing the sequential steps for the manufacture thereof, therein Fig.
16 shows the step of forming a series of multi-facet grooves, Fig. 17 the step of charging oxide glass, Fig. 18 the step of forming a second series of multi-facet grooves, Fig. 19 the step of forming a non-magnetic film having high-hardness, Fig. 20 the step of forming a ferromagnetic metal thin film, Fig. 21 the step of forming the non-magnetic film having high-hardness, Fig. 22 shows the step of charging molten oxide glass and the surface grinding step, Fig. 23 the step of forming the winding slot, and Fig. 24 the step of melt bonding or glass bonding.
Fig. 25 to 33 are perspective views showing the process steps for a third embodiment of the present invention, wherein Fig. 25 shows the step of forming a first series of grooves, Fig. 26 the step of charging the glass with high melting temperature, Fig. 27 the step of forming a second series of grooves, Fig. 28 the step of forming a non-magnetic film having high-hardness, Fig. 29 the step of forming the ferromagnetic metal thin film, Fig. 30 the step of forming a non-magnetic film having high-hardness, Fig. 31 the step of charging molten oxide glass filler and the surface grinding step, Fig. 32 the step of forming the winding slot and ~;235~3 Fig. 33 the step of melt bonding or glass bonding.
Fig, 34 is a perspective view showing the magnetic transducer head manufactured my the process steps of Figs. 25 to 33, Figs, 35 to 37, are perspective views showing three further embodiments of the present invention.
Fig. 38 is a perspective view showing the arrangement of the'con~entional magnetic transducer head.
Description of the Preferred Embodiments To overcome the drawbacks existing in the prior art, we proposed a novel composite type magnetic transducer head suitable for high density recording on high coercive force magnetic tape. The magnetic transducer head is composed of a pair of magnetic core elements 101, 102 of ferromagnetic oxides such as Mn-Zn ferrite, as shown in Fig. 38.
The abutment sides of these core elements are cut obliquely or defining surface 103, 104. On these, the ferromagnetic metal thin films 105, 106, such as Phallus alloy suckled Sendustl are deposited by employing the physical vapor deposition. The magnetic gap 107 is defined by abutting the ISLES

ferromagnetic metal thin films 105, 106 to each other, and glass fillers 108, 109 having low melting point or glass fillers 110, 111 having high melting point are charged in the molten state for procuring the contact surface with the tape and preventing the wear of the ferromagnetic metal thin films 105, 106. The magnetic transducer head is superior in operational reliability, magnetic properties and wear resistance.
However, these composite type magnetic transducer heads suffer from inconveniences especially as to the behavior of the boundary layers between the different kinds of materials, such as the ferromagnetic oxide -ferromagnetic metal thin film - oxide glass boundary layers.
For example, when the ferromagnetic metal thin film is deposited as by sputtering on the ferromagnetic oxide (ferrite), the ferrite interface in contact with the metal is subjected to an elevated temperature in the range of 300 to 700C. This causes the reaction to take place on the ferromagnetic metal thin film -ferromagnetic oxide interface and the oxygen atoms in the ferrite start to be diffused towards an equilibrium state in the temperature range of 300 to 500C so as to be bonded with Al, So and Fe. The result is that the ferrite surface is slightly deoxidized and the ~23S4~3 contents of oxygen atoms are decreased so that the boundary layer with inferiority in the magnetic proper-ties is produced on the interface between the ferrite and the ferromagnetic metal thin film. When the boundary layer with the inferior magnetic properties is produced in this manner, the soft magnetic proper-ties of the ferrite are lowered by increase in the magnetic reluctance in the layer, so that the recording characteristics and reproduction output of the magnetic transducer head is lowered. In addition, the magnetic transducer head is formed by the ferromagnetic metal thin films and the ferromagnetic oxides having different thermal expansion coefficients. For example, the thermal expansion coefficient for Phallus alloy is 130 to 1~0 x 10-7/C., whereas that of the ferrite is 90 to 110 x 10 okay. Thus a stress is necessarily induced in the material in the course of the post-sputtering process such as melt bonding process, resulting in the destruction or breakage of the ferromagnetic metal thin films or deterioration in mechanical properties.
Also, when the glass is directly charged in the molten state after the deposition ox the Phallus alloy, the ferromagnetic metal material may be eroded by some kinds of molten glass. The reaction between the metal and the glass may cause the edge or surface of the ~23~483 ferromagnetic metal thin films to be deformed thus affect-in the material properties or dimensional accuracy.
With some kinds of the materials directly contacting with molten glass, problems are presented such as decreased fluidity or bubbles in the molten glass.
The magnetic transducer head according to a first embodiment of the present invention is firstly explained, in which a ferromagnetic metal thin film is continuously formed from the front side or the contact surface of the head with the magnetic tape to the back side or the back gap forming surface of the magnetic transducer head.
Fig. l is a perspective view showing an example of the composite magnetic transducer head embodying the present invention. Fig. 2 is a plan view showing the contact surface of the head with the magnetic tape, and Fig. 3 is a perspective view of the magnetic transducer head shown exploded along the gap forming surface.
This head is composed of core elements 10, 11 wormed of ferromagnetic oxides, such as Mn-Zn ferrite. On the junction surfaces of the core elements 10, 11, there are formed ferromagnetic metal thin films 13 of ferromagnetic metal or high permeability metal alloy, such as Phallus alloys, by using the physical vapor deposition method, such as sputtering by the medium of non-magnetic films having high-hardness 12. The film 13 are continuously formed from ~23S4~513 the front gap forming surface to the rear gap forming sun-face. These core elements 10, 11 are placed in abutment with each other with the intermediary of a spacer formed of e.g. Sue so -that the abutment surfaces of the thin films 13 are used as a magnetic gap g with a track width Two When seen from the contact surface with the-magnetic tape, the thin films 13 are deposited on the core elements 10, 11 along a straight continuous line inclined an angle e with respect to a magnetic gap forming surface 14 or the junction or abutment surfaces of the magnetic core elements 10, 11.
Non-magnetic films having high-hardness 15 are also formed on the ferromagnetic metal thin films 13. In the vicinity of -the magnetic gap surface or on both sides of a magnetic gap g on the head surface facing to the magnetic tape is filled non-magnetic oxide glass at 16, 17 for defining the track width.
The angle between the ferromagnetic metal thin film forming surfaces loan ha and the magnetic gap forming sun-face 14 is preferably in the range from 20 to 80. The angle e less than 20 is not preferred because of increased crosstalk with the adjoining tracks. Thus, the angle larger than 30 is most preferred. The angle e less than about 80 is also preferred because wear resistance is lowered with the angle equal to 90. The angle e equal to 90 is also ~23~3 not preferred because the thickness of the thin film 13 need to be equal to the track width Two which gives rise to the nonuniform film structure and the time-consuming operation in forming the thin film in vacuum or under reduced pressure.
The deposited metal thin film 13 need only be of a film thickness t such that t = Two sin e wherein Two represents a track width and represents an angle between the surfaces loan ha and the magnetic gap forming surface 14. The result is that the film need not be deposited to a thickness equal to the track width and hence the time required for the preparation of the magnetic transducer head may be notably reduced.
The metal thin films 13 may be formed of the ferry-magnetic metals including Phallus alloys, Fe-Al alloys, Phase alloys, Physique alloys, Nephew alloys (so-called permalloys), ferromagnetic amorphous metal alloys, such as metal-metalloid amorphous alloys, e.g. an alloy of one or more elements selected from the group of Fe, No and Co with one or more elements selected from the group of P, C, B and Six or an alloy consisting essentially of the firstly mentioned alloy and containing Al, Go, Be, Sun, In, Mow W, Tip My, Or, Or, Hi, or Nub, or a metal-metal amorphous alloy consisting essentially of transition metal elements and ~23~ 3 glass forming metal elements such as Hi or Or.
The films 13 may be deposited by any of the vacuum film forming methods including flash deposition, vacuum deposition, ion plating, sputtering or cluster ion beam methods.
Preferably, the composition of the Phallus alloys is so selected the Al contents are in the range from 2 to 10 weight percent, and the So contents are in the range from 4 to 15 weight percent, the balance being Fe. Thus it is preferred that, when the Phallus alloys are expressed as Fe a Al b So c where, a, b, and c represent the weight ratio of the respective associated components, the values of a, b and c are in the range such that a 95 2 b 10 4 _ c _ 15 If the Al or So contents are too low or too high, magnetic properties of the Phallus alloys are lower.
In the above composition, a part of Fe may be replaced by at least one ox Co and Nix The saturation magnetic flux density may be improved by replacing a part of Fe with Co. Above all, the maximum saturation magnetic flux density By may be achieved when ~L235~! 33 40 weight percent of Fe is replaced by Co. Preferably, the amount of Co is 0 to 60 weight percent relative to Fe.
On the other hand, by replacing a part of Fe with Nix magnetic permeability may be maintained at a higher value without lowering the saturation magnetic flux dens-try By. In this case, the amount of No is preferably in the range from 0 to 40 weight percent related to Fe.
Other elements may also be added to the essay alloys for improving its corrosion and wear resistance.
The elements that may be used as such additives may include IIIa group elements including lanthanides such as So, Y, La, Cue, No and Go; Ivy group elements such as Tip Or or Hi;
Via groups such as V, Nub or Tax Via group elements such as Or, My or W; Viva group elements such as My, To or Rev It group elements such as Cut A or A; elements of the plait-nut group such as Rut Rho or Pod; and Gay In, Go, Sun, Sub or Bit When employing the Phallus alloy, the ferromagnetic metal thin films 13 are preferably deposited in such a manner that the direction of the columnar crystal growths be inclined at a predetermined angle of 5 to 45 with respect to a normal line drawn to the surfaces aye, ha of the magnetic core elements 10, if.
When the thin films 13 are caused to grow in this ISLE

manner at a predetermined angle with respect to the normal line drawn to the surfaces loan ha, the magnetic properties of the resulting ferromagnetic metal thin films 13 are stable and superior resulting in improved magnetic properties or the magnetic transducer head.
Although the films 13 are formed as the single layer by the above described physical vapor deposition, a plural-fly of thin metal layers may be also be formed with an electrically insulating film or films such as Sue, Tao, AYE, ZrO2 or Sweeney between the adjacent thin metal layer or layers. Any desired number of the ferromagnetic metal layers may be used for the formation of the metal thin film.
The non-magnetic films having high-hardness 12 inter-posed between the core elements 10, 11 and the metal thin films 13 may be formed of (A) one or more of oxides such i2~ Tao Tao AYE, Cry or the glass with high melting temperature, and deposited to a film thickness of 50 to 2000 A, or formed of (B) non-magnetic metals such as Or, To or So either singly or as an alloy and deposited to a film thickness of 50 to 2000 A. The materials of the groups (A) and (B) may be used separately or concurrently.
An upper limit is set to the non-magnetic films having high-hardness 12 because of the pseudo-gap and since the magnetic reluctance is no longer negligible for a higher film thick-news.

~23~3 By forming the non-magnetic film having high-hardness 15 on the metal thin film 13, the high-output magnetic trays-dicer head may be obtained by reason of the decreased glass erosion, decreased breakage of the ferromagnetic metal thin film 13, improved dimensional accuracy, glass fluidity or yield rate, and dispersion of the residual strain induced by glass bonding. The non-magnetic film having high-hardness 15 may be formed of refractory metals such as W, My or To and oxides thereof, in addition to the materials of the groups (A) and (B) for the non-magnetic films having high-hardness 12. These materials may be used singly or as an admixture, such as Or, Or + Tao + Or, Or + Sue + Or, To + Shea + Tip and are formed to a thickness less than several microns.
- Thus, as shown for example in Fig. 4, a non-magnetic film having high-hardness 12 of the dual layer structure consisting of a Sue layer aye and a Or layer 12b is pro-voided between the core elements 10, 11 and the metal thin film 13, and a non-magnetic film having high-hardness 15 of a triple layer structure consisting of a Or layer aye, Tess layer 15b and a second Or layer 15c may be formed between the metal thin film 13 and the oxide glass 16.
In the above described magnetic transducer heed, the ferromagnetic metal thin films 13 are deposited on the surfaces loan ha of the ferrite core elements 10, 11 ~23~1!33 through the intermediary of the non-magnetic films having high-hardness 12. This prevents the diffusion into the metal thin films 13 of the oxygen atoms of the ferrite on account of the presence of the non-magnetic films having high-hardness 12 even under high temperature conditions prevailing during the sputtering, for preventing the format lion of the boundary layer with inferiority in the magnetic properties. Hence, the soft magnetic properties of the vicinity of the surfaces loan ha connected by a magnetic circuit to the metal thin film 13 are not deteriorated so that the reduction in the recording characteristics and playback output of the magnetic head is prevented from occurring. Also, since the surfaces loan ha on which are formed the magnetic metal thin films 13 are inclined at a certain angle with respect to the magnetic yap forming surface 14, pseudo gaps are not induced even when the non-magnetic films having high hardness 12 are of a certain film thickness. The film 12 with too large a thickness is however not desirable for the proper function of the magnetic circuit.
Upon comparative tests on the playback output of the magnetic transducer head with that of the conventional magnetic head have revealed that an increase in the output level of the order of 1 to 3 dub may be obtained with the signal frequency e.g. of 1 to 7 MHz.
Since the aforementioned boundary layer is not formed ~L235~3 during the sputtering step, limitations on the sputtering speed or temperature may be removed partially resulting in the facilitated manufacture of the transducer head.
Also, since the thermal stress induced by the differential thermal expansion between the ferrite core elements 10, 11 and the ferromagnetic metal thin films 13 is relaxed by the presence of the non-magnetic films having high-hardness 12, no cracks are formed in the metal thin film 13 even upon cooling following the sputtering or upon heating caused by subsequent step of glass melting. This is also favorable in improving the magnetic properties.
Likewise, since the non-magnetic film having high hardness 15 is formed between the film 13 and the oxide glass 16, it is possible to inhibit the elongation of the ferromagnetic metal thin films 13 or to provide only a so-called short-range strain by dispersing the strain induced between the core elements 10, 11 and the oxide glass 16. Cracks or wrinkles in the films 13 are also prevented for improving the operating reliability of the magnetic head and the yield rate in the manufacture of the transducer head.
It should be noted that the non-magnetic films having high-hardness may be provided on the interface between the core elements 10, 11 and the metal thin films 13 as shown ~23~3 in Fig. 5 or on the interface between the metal thin films 13 and the oxide glass 16 as shown in Fig. 6. In Figs. 5 and 6, the same parts or components as those shown in Fig.
1 are indicated by the same reference numerals.
The manufacture process of the above described em-bodiment will be explained for clarifying the structure of the magnetic transducer head.
In preparing the magnetic transducer head of the present embodiment, a plurality of parallel vie grooves 21 are transversely formed on the upper surface aye of a substrate 20 of ferromagnetic oxides, such as Mn-Zn ferrite, with the aid of a revolving grindstone, for forming a sun-face 21 on which to deposit the ferromagnetic metal thin films (Fig. 7). The upper surface aye represents the junk-lion or abutment surface of the ferromagnetic oxide substrate 20 with the corresponding surface of a mating substrate.
I've surface 21 is formed as an inclined surface having a present angle of inclination 0 (equal to about 45c ion the present embodiment) with respect to the magnetic gap form-in surface of the substrate 20.
Then, as shown in Fig. 8, a nonmagnetic film having high-hardness 22 is formed as by sputtering on the upper surface aye of the ferromagnetic oxide substrate 20. This film 22 is formed by providing a first non-magnetic film having high-hardness by depositing e.g. Sue to a thickness ~23.~

of 300 A and a second non-magnetic film having high-hardness by depositing a Or film to a thickness of 300 A on the first non-magnetic film having high-hardness.
Then, as shown in Fig. 9, Phallus alloy or amorphous alloy is applied to the non-magnetic film having high-hardness 22 by employing any of the physical vapor deposit lion such as sputtering, ion-plating or vacuum deposition, for providing the ferromagnetic metal thin film 23.
Then, as shown in Fig. lo a non-magnetic film having high-hardness 24 is also formed on the ferromagnetic metal thin film 23. The film 24 is formed by applying a first Or film to a thickness of approximately 0.1 em, then apply-in a Tao film to a thickness of l em and finally apply-in a second Or film to a thickness of approximately 0.1 em.
The film 24 is preferably formed of high-melting metal such as W, Mow So or Tax oxides or alloys thereof, and deposited to a thickness less than several microns. The bonding of the non-magnetic film having high-hardness 24 to the ferry-magnetic metal thin film is improved by the first Or film.
Then, as shown in Fig. if, on oxide glass filler 25 such as the glass with the low melting point is filled in the first grooves 21 in which the films 23, 22, 24 are pro-piously deposited. The upper surface aye of the substrate 20 is ground smooth for exposing on the upper surface aye ~23-15~3 the ferromagnetic metal thin film 23 deposited on the surface aye.
Then, as shown in Fig. 12, adjacent to the surface aye on which is previously applied the ferromagnetic metal thin film 23, a second groove 26 is cut in parallel to the first groove 21 and so as to slightly overlap with one side edge aye of the first groove 21. The upper surface aye of the substrate 20 is then ground to a mirror finish. As a result of this process step, the track width is regulated in such a manner that the magnetic gap is delimited solely by the ferromagnetic metal thin film.
The second groove 26 may also be polygonal in cross-section instead of being vie shaped and the inner wall surface of the groove 26 may be stepped with two or more stages for procuring a distance from the ferromagnetic oxide and the ferromagnetic metal thin films when viewed from the contact surface with the tape. With the groove configuration, it is possible to reduce the crosstalk otherwise caused by the reproduction of the long wave-length signals may be reduced while the large junction area between the ferromagnetic oxide and the ferromagnetic metal thin film is ensured. Also, with the above groove configuration, the end face of the ferromagnetic oxide is inclined in a direction different from the azimuth angle direction of the magnetic gap so that signal pickup 3L~23.~ 3 from the adjoining or next adjoining track or crosstalk may be reduced by virtue of the azimuth loss.
Also, since the ferromagnetic metal thin film 23 is first formed on the surface aye and the second groove 26 is then formed for the regulation of the track width, it is possible to manufacture the magnetic transducer head with high yield rate and high accuracy of the track width by adjusting the machining position of the second groove 26. Thus, when the transducer head is of the type in which the magnetic flux is passed through the ferromagnetic oxide via a minimum distance from the magnetic gap formed only by the ferromagnetic metal thin film, the output and product tivity as well as operating reliability of-the head are improved with low manufacture costs.
A pair of similar ferromagnetic oxide substrates 20 are formed by the above described process. A groove is cut on one of the substrates at right angle with the first groove 21 and the second groove 26 for providing a ferromagnetic oxide substrate 30 provided with a winding slot 27 (Fig. 13).
A gap spacer is then applied on the upper surface aye of the substrate and/or the upper surface aye of the sub-striate 30. Then, as shown in Fig. 14, these substrates 20, 30 are positioned with the respective metal thin films 23 abutting to each other. These substrates 20, 30 are bonded with molten glass while simultaneously the second groove 26 ~23~33 is charged with molten glass 28. The gap spacer may be formed of Sue, ZrO2, Tacos or Or, as desired. In the above process, charging of the glass 28 in the second groove 26 need not be effected simultaneously with the bonding of the substrates 20, 30. Thus the glass 28 may be charged in the step shown e.g. in Fig. 13 so that the step shown in Fig. 14 may consist only of the glass bond-in step.
The superimposed substrates 20, 30 may then be sliced along e.g. lines A-A and AYE' in Fig. 14 for producing a plurality of head chips, and the contact surface of each head chip with the magnetic tape is then ground to a cylindrical surface for providing the magnetic transducer head shown in Fig. 1. The slicing direction through the substrates 20, 30 may be inclined with respect to the abutment surface for providing the azimuth recording mug-netic transducer head.
It should be noted that one of the core elements 10 consists essentially of the ferromagnetic oxide substrate 20 while the other core element 11 consists essentially of the ferromagnetic oxide substrate 30. The ferromagnetic metal thin film 13 corresponds to the ferromagnetic metal thin film 23 and the non-magnetic films having high-hardness 12, 15 correspond to the non-magnetic films having high-hardness 22, 24, respectively. The ferromagnetic metal thin film 23 formed on a planar surface exhibits high unit form magnetic permeability along the path of magnetic flux.
The magnetic transducer head according to a modified embodiment in which the ferromagnetic metal thin film is formed only in the vicinity of the magnetic gap is here-after explained by referring to Fig. 15.
In the present embodiment, the ferromagnetic metal thin film is formed only in the vicinity of the magnetic gap of the magnetic transducer head, wherein a pair of magnetic core elements 40, 41 are formed of ferromagnetic oxides such as Mn-Zn ferrite and the ferromagnetic metal thin films 42 are formed only on the front depth side in the vicinity of the magnetic gap g by applying the high permeability alloy such as Phallus alloy thereto by the physical vapor deposition such as sputtering. Oxide glass fillers 43, 44 are charged in the molten state in the vi-Senate of the gap forming surface. The non-magnetic films having hurriedness 45 consisting, for example, of oxides such as Sue, Shea or Tao or non-magnetic metals such as Or, To or So are provided between the ferromagnetic metal thin films 42 and the magnetic core elements 40, 41 of ferromagnetic oxides, as in the preceding embodiment.
Non-magnetic films having high-hardness 46 consisting, for example, of refractory metals or oxides thereof, such as Tao, Or, Shea or Sue, are provided between the metal thin ~L23~ 3 films 42 and the oxide glass fillers 43. The metal thin films 42 are inclined at a preset angle relative to the magnetic gap forming surface when seen from the contact surface with the tape, as in the preceding embodiment.
The magnetic transducer head may be manufactured by the manufacture process steps shown in Figs. 16 to 24.
Firstly, as shown in Fig. 16, a plurality of grooves 51 of polygonal cross-section are formed on one longitude-net edge of the ferromagnetic oxide substrate 50 of Mn-Zn ferrite by means of a rotary grindstone or with the aid of electrolytic etching. The upper surface aye of the substrate 50 corresponds to the magnetic gap forming surface and the multi-facet groove 51 is provided in the vicinity of the magnetic gap forming position of the substrate 50.
Then, as shown in Fig. 17, oxide glass fillers 52 are filled in the molten state in the groove 51, and both the upper surface aye and the front surface 50b are ground smooth.
Then, as shown in Fig. 18, a plurality of vie grooves 53 are formed on the substrate edge so as to be adjacent to and partly overlap with the one facet of the groove 51 in which the glass filler is previously filled as described hereinabove. At this time, part of the glass 52 is exposed on the facet or inner wall surface aye of the groove 53.
The line of intersection 54 between the inner wall surface 123S~83 aye and the upper surface aye is normal to the front surface 50b of the substrate 50. The angle the inner wall surface aye makes with the upper surface may for example be 45.
Then, as shown in Fig 19, Sue is applied to a thickness of, for example, 300 A so as to cover at least the grooves 53 of the substrate 50. Then, Or is applied to a thickness of 300 A for providing a non-magnetic film having high-hardness 55.
Then, as shown in Fig. 20, a high permeability alloy such as Phallus alloy is formed in the vicinity of the grooves 53 over the non-magnetic film having high-hardness 55 by any of the above described physical vapor deposition such as sputtering, for providing the ferromagnetic metal thin film 56. During formation of the metal thin film 56, the substrate 50 may be disposed with a tilt in the sputtering apparatus so that the ferromagnetic metal may be efficiently deposited on the facet or inner wall surface aye of the groove 53.
On the thus deposited metal thin film 56, the non-magnetic film having high-hardness 57 formed of, for example, Tao, Shea or Sue is deposited as by sputtering (Fig. 21).
In the present example, the dual non-magnetic film having high-hardness 57 is formed by applying a Or film on the metal thin film 56 to a thickness owe 0.1 em by sputtering and applying a Tacos film thereon to a thickness of ;

~23S~33 approximately 1 em, also by sputtering. By thus forming the Or film on -the metal thin film 56, the state of deposition of the Tacos film on the metal thin film is improved.
Although the non-magnetic film having high-hardness 57 of the present embodiment consists of the Or and Tacos layers, it may also be formed by depositing the Crochets lay-ens in this order or by depositing the To film to about 1 em and the Shea layer to about 1 em in this order.
Then, in the groove 58 in which the non-magnetic film having high-hardness 55, the ferromagnetic metal thin film or layer 56 and the non-magnetic film having high-hardness 57 are deposited one upon the other, the oxide glass 58 lower melting than the oxide glass 52 is filled in the molten state (Fig. 221. The upper surface aye and the front surface 50b of the substrate 50 are ground to a mirror finish. On the front surface 50b of the substrate 50, the ferromagnetic metal thin film 56 formed on the inner wall surface aye of the groove 53 is sandwiched between the previously applied non-magnetic films having high-hardness 55, 57.
For forming the winding slot side magnetic core eye-mint, a winding slot 59 is cut in the ferromagnetic oxide substrate 50 previously processed as described above (Fig.
22) for providing the ferromagnetic oxide substrate 70 shown in Fig. 23.

~L23~33 The substrates 50, 60 are abutted to each other as shown in Fig. 24, with the upper or magnetic gap forming surface aye of the substrate 50 in contact with the upper or magnetic gap forming surface aye of the substrate 60 by the intermediary of a gap spacer affixed to one of the upper surfaces aye, aye, and are bonded together by molten glass to a composite block which is then sliced along lines B-B and BY in Fig. 24 for providing a plurality of head chips. The slicing operation may also be performed with the block inclined azimuth angle.
The contact-surface of the head chip with the magnetic tape is ground to a cylindrical surface for come pleating the magnetic transducer head shown in Fig. 15.
It should be noted that one of the magnetic core eye-mints 41 of the magnetic transducer head shown in Fig. 15 consists essentially of the ferromagnetic oxide substrate 51, while the other core element 40 consists essentially of the ferromagnetic oxide substrate 60. The non-magnetic films having high-hardness 45, 46 correspond to the non-magnetic films having high-hardness 55, 57, respectively, whereas the ferromagnetic metal thin film 42 corresponds to the ferromagnetic metal thin film 56. The oxide glass filler 43 corresponds to the oxide glass filler 58.
With the magnetic transducer head constructed as described hereinabove, the ferromagnetic metal thin film 42 ~3~3 exhibits a high uniform magnetic permeability along the direction of the path of magnetic flux thus assuring a high stable output of the magnetic transducer head. Also the ferromagnetic metal thin film is protected by the non-magnetic films having high-hardness 45 against cracking or deformation.
Also, with the magnetic transducer head of the present embodiment, the ferromagnetic oxides are directly bonded together by glass on the back junction surface or back gap surface thus providing large destruction strength of the head chip and improved yield rate while assuring stability of the ferromagnetic metal thin film. Also, since the metal thin film is formed only in the vicinity of the mug-netic gap g, the metal thin film 42 need be formed on a relatively small area. Thus the number of items disposable in one lot in the sputtering apparatus may be increased resulting in improved mass producibility.
A further example of the magnetic transducer head manufactured by an alternative process is explained by referring to Figs. 25 to 34.
In preparing the magnetic transducer head, as shown in Fig. 25, a plurality of square shaped grooves 71 are formed obliquely on the upper surface aye corresponding to the contact surface with the magnetic tape of the ferry-magnetic oxide substrate 70 formed erg. of Mn-Zn ferrite.

~235~!~3 The grooves 71 are of such a depth as to reach the winding slot of the head.
Then, as shown in Fig. 26, the glass filler 72 having the high melting temperature is filled in the molten state in the grooves 71. The upper surface aye and the front surface job are then ground smooth.
Then, as shown in Fig. 27, a plurality of second square shaped grooves 73 are formed on the upper surface aye in the reverse oblique direction to and for partially overlapping with the first square shaped grooves 71 filled previously with the glass filler 72. The groove 73 is of nearly the same depth as the groove 71. The inner side aye of the groove 73 is normal to the upper surface aye of the substrate 70 and makes an angle of e.g. 45 with the front surface 70b. The inner side aye of the groove 73 intersects the associated first groove 71 in the vicinity of the front side 70b of the substrate 70 for slightly cutting off the glass filler 72.
After the grooves 71, 73 are formed in this manner on the upper surface aye of the ferromagnetic oxide substrate 70, a non-magnetic film having high-hardness I of e.g. Sue or Or is deposited in the vicinity of the groove 73 of the substrate 70, as shown in Fig. 28, by employing any of the above described physical vapor deposition, such as sputter-in. The non-magnetic film having high-hardness 74 may be ~235~3 formed of the same materials as explained in the preceding embodiments.
Then, as shown in Fig. 29, a high permeability alloy layer, such as Phallus alloy layer is formed on the film 74 for providing a ferromagnetic metal thin film 75 by employing any of the above described physical vapor deposit lion, such as sputtering. The substrate 70 may be disposed with a tilt in the sputtering apparatus for achieving an efficient deposition of the alloy layer.
Then, as shown in Fig. 30, high-hardness metals, oxides or alloys thereof are applied to the film 75 as by sputtering, for providing the non-magnetic film having high-hardness 76. The non-magnetic film having high-hardness 76 may be formed of the same materials as explained in the preceding embodiments in one or plural layers.
Then, as shown in Fig. 31, in the grooves 73 in which the nonmagnetic films having high-hardness films 74, 76 and the ferromagnetic metal thin film 75 are deposited one upon the other, an oxide glass filler 77 lower melting than the glass filler 72 charged in the groove 71 is charged in the molten state. The upper surface aye and the front surface 70b of the substrate 70 are ground to a smooth mirror finish. The result is that the metal thin film 75 is sandwiched and protected by the non-magnetic films having high-hardness 74, 76 on the inner side aye of the ~3~0~

groove 73. Al-though the films 74, 75, 76 persist on the other inner side and bottom of the groove 73, they are in negligible amounts and hence are not shown in the drawing.
Then, a winding slot 78 is cut on one of the sub-striates for providing the ferromagnetic oxide substrate 80 (Fig. 32).
Then, as shown in Fig. 33, the substrate 80 provided with the winding slot 80 and the substrate 70 not provided with the winding slot are placed side by side with the intermediary of a gap spacer deposited on at least one of the magnetic gap forming front surface 70b, 80b, so that the metal thin films abut each other. The substrates 70, 80 are then united together by glass or melt bonding to a unitary block.
The block thus formed by the substrates 70, 80 are sliced along lines C-C and C'-C' in Fig. 33 for forming plural head chips. The abutting surfaces of these head chips with the magnetic tape are then ground to a cylinder-eel surface for completing the magnetic transducer head shown in Fig. 34.
With the magnetic transducer head shown in Fig. 34, one of the magnetic core elements 81 corresponds to the ferromagnetic oxide substrate 70, while the remaining core element corresponds to the ferromagnetic oxide substrate 80. The ferromagnetic metal thin film 84 corresponds to the ferromagnetic metal thin film 75, whereas the non-magnetic films having high-hardness 83, 85 correspond to the non-magnetic films having high-hardness 74, 76, respectively. The oxide glass filler 86 corresponds to the oxide glass filler 77.
In the magnetic transducer head shown in Fig. 34, the ferromagnetic metal thin film 84 is sandwiched and protected by the non-magnetic films having high-hardness 83, 85 against cracking, deformation or deterioration in the boundary surface with the ferromagnetic oxides, semi-laxly to the preceding embodiments, so that optimum results are achieved as in the case of the magnetic transducer heads shown in Figs. 1 and 15. The metal thin film I is inclined at a preset angle to the surface forming the magnetic gap g and is formed linearly and continuously on one and the same surface thus assuring a high uniform magnetic permeability along the path of magnetic flux and providing a high stable output, as in the preceding embodiments.
The present invention is also applied to a magnetic transducer head in which the vicinity of the contact surface with the magnetic tape is protected by the non-magnetic elements having high-hardness, such as ceramic elements.
Figs. 35 to 37 show an embodiment of the magnetic transducer head in which the vicinity of the contact 12;~5~93 surface with the magnetic tape is protected by non-magnetic elements having high-hardness, such as ceramic elements.
The magnetic transducer head shown in Fig. 35 corresponds to that shown in Fig. 1 so that components same as those shown in Fig. 1 are indicated by the same reference numerals. Thus the magnetic transducer head shown in Fig. 35 corresponds to the head of Fig. 1 where-in the protective elements 91, 92 formed of non-magnetic wear-resistant materials such as calcium titan ate (Tokyo ceramics), oxide glass chips, titanic (Shea) or alumina (Aye) are provided in the vicinity of the contact surface with the magnetic tape. The transducer head of Fig. 35 consists essentially of a composite substrate formed by thermal pressure bonding of a highly wear-resistant non-magnetic substrate of e.g. calcium -titan ate, oxide glass, titanic or alumina to one end face of a ferromagnetic oxide substrate of e.g. Mn-Zn ferrite with the intermediary of a molten glass plate about several tens of microns thick. The substrate is processed in accordance with the process similar to that shown in Figs.
7 to 14. Since the magnetic material such as ferrite is not exposed on the contact surface with the magnetic tape, the machining step shown in Fig. 12 for forming the second groove 26 may be dispensed with.

1231 ~31r3 The magnetic transducer head shown in Fig. 36 cores-ponds to the magnetic transducer head shown in Fig. 15 and the components same as those shown in Fig. 15 are indicated by the same reference numerals. The magnetic transducer head shown in Fig. 36 corresponds to the magnetic transducer head shown in Fig. 15 in which protective elements 93, 94 of highly wear-resistant non-magnetic material are provided to the vicinity of the contact surface with the magnetic tape. The magnetic transducer head shown in Fig. 36 is fabricated from the similar composite substrate and by the manufacture process shown in Figs. 16 to 24. In this case, the machining step for the groove 51 shown in Fig.
16 and the charging step of the molten oxide glass filler 52 shown in Fig. 17 may be dispensed with.
The magnetic -transducer head shown in Fig. 37 core-spends to the magnetic transducer head shown in Fig. 34 and the components same as those of the magnetic transducer head sown in Fig. 34 are indicated by the same reference numerals. The transducer head shown in Fig. 37 corresponds to the head shown in Fig. 34 in which protective elements 95, 96 of highly wear-resistant non-magnetic material are provided in the vicinity of the contact surface with the magnetic tape. The magnetic transducer head of the present embodiment is fabricated from the composite substrates of the preceding embodiments and by using the process :~23~ 3 similar to that shown in Figs. 25 to 33. In this case, the machining step of forming the groove 71 as shown in Fig. 25 and the charging step of the high melting glass filler 72 in the molten state as shown in Fig. 26 are similarly dispensed with.
In the respective magnetic transducer heads shown in Figs. 35 to 37, wear-resistant non-magnetic elements are previously bonded to the ferromagnetic oxide block and ground for forming the abutting surface with the mug-netic type. In this manner, the portion of the abutting surface, inclusive of the gap surface, other than the magnetic metal thin film, is constructed of the non-magnetic materials, that is, the wear-resistant non-magnetic material and the non-magnetic films having high-hardness, so that the ferromagnetic oxide material is not exposed to the out-side. Thus the track width is determined by the size of the inclined section of the ferromagnetic metal thin film irrespective of the terminal point of the gap surface grinding operation following the formation of the ferry-magnetic metal thin film, thus allowing for broader menu-lecture tolerance of the substrate block. Also the ferry-magnetic metal thin film is protected by the non-magnetic film having high-hardness, so that the magnetic transducer head is protected from deformation, cracking or degradation on the boundary layer in the course of glass bonding, thus ~23~33 assuring a high yield rate and a high stable output of the magnetic transducer head. In VTR heads, it is necessary to make use of single crystal ferrite projecting on the tape abutment surface because of the increased relative speed between the head and the tape, resulting in increased material costs. In the above described embodiments, the back gap side ferrite is not likely to undergo partial wear upon contact with the tape so that Howe polycrystal ferrite (i.e. sistered type polycrystal ferrite) may be safely used with an-attendant reduction in the material costs.
It will be apparent from the foregoing that the pro-sent invention provides an arrangement of the magnetic transducer head according to which non-magnetic film having high-hardness are interposed between the ferromagnetic metal thin film and the ferromagnetic oxides so that the diffusion of the oxygen atoms in the ferromagnetic oxides is prevented even under the elevated temperature during the time of application of the ferromagnetic metal thin film and hence there is no risk that the boundary layer with inferiority in magnetic properties due to low oxygen atom contents in not wormed in the boundary layer with the ferromagnetic oxides. The result is that the soft magnetic properties of the ferromagnetic oxides are not deteriorated and the recording characteristics and playback output of the magnetic transducer head is also not lowered.

~Z3~ 3 Since the boundary layer with inferior magnetic prop-reties is not induced by sputtering, limitations on the sputtering speed or temperature in the course of applique-lion of the ferromagnetic metal thin film can be removed partially with a resulting merit in manufacture efficiency.
The non-magnetic film having high-hardness interposed between the oxide glass filler and the ferromagnetic metal thin film is effective to protect the oxide glass and improve glass fluidity while inhibiting the erosion by the oxide glass or the deformation of the ferromagnetic metal thin film.
The provision of the respective non-magnetic films having high-hardness is also effective to improve the bonding of the ferromagnetic metal thin film and to par-tidally remove local stress such as thermal stress otherwise caused by the differential thermal expansion between the adjoining components during the post-sputtering process such as cooling process for preventing crack or the like defects.
Therefore the ferromagnetic metal thin film is more stable and the magnetic properties are also stable with an improved accuracy in the track width so that the magnetic transducer head is reliable in strength and ma be con-leniently used with a high coercive force magnetic recording medium.

Claims

WHAT IS CLAIMED IS

1. A magnetic transducer head comprising:
a first and a second magnetic core element bonded together having an operating magnetic gap between first planar surfaces of each of said magnetic core elements, and a contact surface for a travelling magnetic recording medium;
each of said magnetic core elements having a third surface extending adjacent to said first planar surface and said contact surface;
said core element comprising a magnetic ferrite block having a second planar surface extending from said first planar surface to a side of said third surface;
a magnetic metal thin film formed of said second planar surface extending from said first planar surface to said side of said third surface along a line not perpendicular to said magnetic gap as viewed on said contact surface;
a non-magnetic material portion extending to said first planar surface, said contact surface and said third surface; and a non-magnetic film having high-hardness interposed between said magnetic metal thin film and said non-magnetic material portion;
said first and said second core elements being bonded in such manner that said operating magnetic gap is formed between edges of said magnetic metal thin film appearing on said first planar surface of each of said core elements, and said line of said first core element and said second core element exist on a common straight line as viewed on said contact surface.

2. A magnetic transducer head according to claim 1, wherein said operating magnetic gap is provided at the central portion of said contact surface.

3. A magnetic transducer head according to claim if wherein an angle of said first planar surface and said second planar surface as viewed on said contact surface is between 20° and 80°.

4. A magnetic transducer head according to claim 1, further comprises an opening for winding coil provided on at least one of said core elements facing to said first planar surface, deviding said operating magnetic gap and a back gap, and a coil wound through said opening.

5. A magnetic transducer head according to claim 4, wherein said magnetic metal thin film is provided to extend to said back gap.

6. A magnetic transducer head according to claim 4, wherein said back gap is formed between each of said ferrite blocks of said core element.

7. A magnetic transducer head according to claim 1, wherein said magnetic metal thin film has substantially uniform columnar structure over entire area of said magnetic metal thin film.

8. A magnetic transducer head according to claim 1, wherein said magnetic metal thin film is crystalline alloy.

9. A magnetic transducer head according to claim 1, wherein said magnetic metal thin film is Fe - Al - Si alloys.

10. A magnetic transducer head according to claim 1, wherein said magnetic metal thin film has substantially uniform characteristics of magnetic anisotropy over entire area of said magnetic metal thin film.

11. A magnetic transducer head according to claim 1, wherein said magnetic metal thin film is amorphous alloy.

12. A magnetic transducer head according to claim 1, wherein said magnetic metal thin film is metal-metalloid amorphous alloys.

13. A magnetic transducer head according to claim 1, wherein said magnetic metal thin film is metal-metal amorphous alloys.

14. A magnetic transducer head according to claim 1, wherein said non-magnetic film having high-hardness is non-magnetic oxide or non-magnetic metal or alloy thereof or metal having high melting point or oxide therof.

15. A magnetic transducer head according to claim 14, wherein said non-magnetic oxide is selected from the group consisting of SiO2, TiO2, TaO5, Al2O3, CrO3, glass having high melting point.

16. A magnetic transducer head according to claim 14, wherein said non-magnetic metal or alloy thereof is selected from the group consisting of Cr, Ti, Si.

17. A magnetic transducer head according to claim 14, wherein said metal having high melting point or oxide thereof is selected from the group consisting of W, Mow Ta.

18. A magnetic transducer head according to claim 1, further comprises cut out portions formed on each of said core elements extending to said first planar surface, said contact surface and a surface opposite to said third surface.