GB2153581A - Magnetic transducer heads - Google Patents

Magnetic transducer heads Download PDF

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Publication number
GB2153581A
GB2153581A GB08432443A GB8432443A GB2153581A GB 2153581 A GB2153581 A GB 2153581A GB 08432443 A GB08432443 A GB 08432443A GB 8432443 A GB8432443 A GB 8432443A GB 2153581 A GB2153581 A GB 2153581A
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GB
United Kingdom
Prior art keywords
magnetic
metal thin
thin film
transducer head
head according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08432443A
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GB8432443D0 (en
GB2153581B (en
Inventor
Tomio Kobayashi
Heikichi Sato
Makoto Kubota
Shoichi Kano
Tatsuo Kumura
Kazushi Yamauchi
Yoshimi Takahashi
Junichi Saito
Seiki Konno
Osamu Maniwa
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sony Corp
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Sony Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP58250988A external-priority patent/JPS60229210A/en
Priority claimed from JP59078242A external-priority patent/JPS60223012A/en
Priority claimed from JP9975184A external-priority patent/JPS60243810A/en
Application filed by Sony Corp filed Critical Sony Corp
Publication of GB8432443D0 publication Critical patent/GB8432443D0/en
Publication of GB2153581A publication Critical patent/GB2153581A/en
Application granted granted Critical
Publication of GB2153581B publication Critical patent/GB2153581B/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3163—Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional layers for masking, using energy or particle beams for shaping the structure or modifying the properties of the basic layers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/187—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
    • G11B5/1871—Shaping or contouring of the transducing or guiding surface
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3109—Details
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3109—Details
    • G11B5/3116—Shaping of layers, poles or gaps for improving the form of the electrical signal transduced, e.g. for shielding, contour effect, equalizing, side flux fringing, cross talk reduction between heads or between heads and information tracks

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Magnetic Heads (AREA)

Abstract

A magnetic transducer head comprises a first magnetic core element 80 and a second magnetic core element 81, each comprising a magnetic ferrite block and a magnetic metal thin film 82 integrated with the magnetic ferrite block. The core elements 80 and 81 have a first planar surface and a second planar surface. The magnetic metal thin film 82 is provided on the second planar surface and has an edge thereof facing the first planar surface, and the second planar surface is inclined with respect to the first planar surface. The core elements 80 and 81 are bonded together to form an operating magnetic gap g between the edge of the magnetic metal thin film 82 on the first core element 80 and the edge of the magnetic metal thin film 82 on the second core element 81, and the magnetic metal thin film 82 on the first core element 80 and the magnetic thin film 82 on the second core element 81 are formed in one common plane. <IMAGE>

Description

SPECIFICATION Magnetic transducer heads This invention relates to magnetic transducer heads and to methods of manufacturing magnetic transducer heads, and more particularly to such heads formed of composite magnetic material such as ferromagnetic oxide material and ferrormagnetic metal material.
With increase in recording density on magnetic tapes used as recording media for video tape recorders (VTRs), magnetic tapes having a high residual flux density Br and a high coercive force Hc, for example, metal magnetic tape, in which metal magnetic powder is coated on a non-magnetic substrate with a binder to form a magnetic recording layer, are being increasingly used. When a magnetic transducer head is to be used with a metal tape, the magnetic field strength of the magnetic gap of the head must be increased because of the high coercive force of the tape. It is also necessary to reduce the track width of the magnetic transducer head with increase in recording density. Various magnetic transducer heads have been proposed to meetthese demands, such as the magnetic transducer head with a narrow track width shown in Figure 1 of the accompanying drawings.The major portion of the magnetic transducer head shown in Figure 1 is formed of glass or like non-magnetic materials 1A and 1 B, and a ferromagnetic metal thin film 2 having a thickness equal to the track width is sandwiched between the non-magnetic materials 1A and 1 B centrally of the magnetic head. The metal thin film 2 is prepared by forming a high permeability alloy such as Sendust (Fe-Al-Si alloys) on the nonmagnetic material 1A in the form of a core half by physical vapour deposition, such as sputtering.
While the track width can be reduced in this manner, the path of magnetic flux is defined only by the metal thin film 2, and hence the operational efficiency is lowered by reason of increased magnetic reluctance.
The metal thin film 2 needs to be formed to a film thickness equal to the track width by the physical vapour deposition. Hence the preparation of the magnetic head is time-consuming in view of the low deposition rate achievable. Since the metal thin film 2 needs to be formed on a large area, the number of items that can be dealt with by a sputtering unit is necessarily limited, so that the heads cannot be mass-produced efficiently. The metal thin films 2 of extremely small film thicknesses are placed in contact with each other for formation of the magnetic gap of the magnetic transducer head, with the result that accuracy in the gap size and hence the operational reliability are lowered.
The previously proposed magnetic transducer head shown in Figure 2 of the accompanying drawings is prepared in such a manner that, for increasing the magnetic field strength of the magnetic gap, ferromagnetic metal thin films 4 such as Sendust are formed on the magnetic gap forming surfaces of the core halves of ferromagnetic oxide cores 3 by using physical vapour deposition, such as sputtering, and the core halves are bonded together by glass 5. Although the magnetic reluctance of the magnetic transducer head of Figure 2 formed of the composite magnetic material can be made lower than in the case of the transducer head shown in Figure 1, the ferromagnetic metal thin films 4 are formed in a direction normal to the path of magnetic flux so that the playback output is lowered because of eddy current loss.Additional gaps may also be formed between the ferromagnetic oxide cores 3 and the ferromagnetic metal magnetic films 4 thus detracting from the operational reliability of the transducer head.
Also previously proposed is a magnetic transducer head formed of composite magnetic material and having its magnetic gap forming surface inclined with respect to its surface forming the ferromagnetic metal film. For example,#igure 3 of the accompanying drawings shows in plan view the contact surface with the magnetic tape of the magnetic transducer head described in a Japanese Patent Kokai No.
58/155513.
The magnetic transducer head shown in Figure 3 comprises core halves or core elements 150 and 151 formed of ferromagnetic oxides, such as Mn-Zn ferrite. Ferromagnetic metal thin films 155 and 156 such as Sendust are deposited on both sides of and astride ferrite portions 153 and 154 projecting towards a surface forming a magnetic gap 152. The numeral 157 designates a reinforcing glass material.
The magnetic gap 152 of the head is formed by the thin films 155 and 156 of a ferromagnetic metal material deposited in the neighbourhood of the free ends of the projecting ferrite portions 153 and 154.
With the ferromagnetic metal thin films 155 and 156, the growth direction of the columnar grain structure at the free ends of the projecting ferrite portions 153 and 154 is different from that at the inclined sides thereof, as the crystals grow on both sides in parallel and uniformly with a constant angle relative to said sides whereas the crystals growth at the free ends are in a fan shape, that is, the crystals are spread apart towards their distal ends. The result is that the magnetic permeability of the ferromagnetic metal thin films 155 and 156 formed on the free ends is lowered with resultingly lowered recording characteristics and playback output of the magnetic head.
The way in which the surface conditions of, for example, the ferrite substrate surface affect the film forming process when the ferromagnetic metal thin film is formed by physical vapour deposition on the ferrite substrate will now be considered.
In general, a thin magnetic film to be formed by a physical vapour deposition process is affected in known manner by the under-layer conditions. Besides the crystal structure of the substrate and of the underlayerfilm formed as an extremely thin underlayer on the substrate, also noteworthy are the geometrical configuration and uniformity ofthe substrate surface.
Figure 4A of the accompanying drawings is a photograph taken with a scanning electron microscope (SEM) of a two-layered Sendust film formed by sputtering on the ferrite substrate with a SiO2 film 500 angstroms thick between the Sendust layers.
This figure shows, along with another SEM photo graph of Figure 5A of the accompanying drawings, the effect of the ferrite substrate surface configurations on the film formation. Figures 4B and 5B of the accompanying drawings are sketches showing only the main features appearing in the photographs of Figures 4A and 5A, respectively.
Figure 4A shows the Sendust film formed on a planar ferrite substrate surface. As seen from this photograph, Sendust film surfaces 1 59A and 159B formed on the planar surface are uniform and the growth of the columnar grain structure of the crystals appearing in sections 160A and 160B of the Sendust film is uniform and extends parallel to the thickness of the film. In this photograph, the broken section is taken not only of the Sendust film but of the ferrite substrate, and the broken section is viewed with the scanning electron microscope from an oblique direction. On the section of the ferrite substrate 161 is seen the section 160A of the first Sendust layer followed by the section 160B of the second Sendust layer. The film surfaces 159A and 159B belong to the first and second Sendust layers, respectively.The thin lines appearing on the surface 159B of the second Sendust layer represent micro line imperfections on the polished surface of the ferrite slice propagated to the Sendust film and do not affect the magnetic permeability of the film. The photograph is shown with the upper side down and vice versa.
Figure 5A shows the Sendust film formed on an irregular surface of the ferrite substrate. The photograph shows the irregular surface 162 of the Sendust film corresponding to the original irregular surface ferrite substrate. This is indicative of the competitive growth of the crystal grains that is not observed when the crystals are allowed to grow on a smooth planar surface. Also the direction of the columnar crystal growths are not parallel, as may be seen in a section 163 of the Sendust film, but the columnar crystal growths are spread apart in a fan shape on the protuberant portions of the ferrite substrate. In this SEM photograph, the broken section is taken not only of the Sendust film but of the ferrite substrate and the viewing direction is from the oblique upper side. A Sendust film section 163 is seen above a ferriate substrate section 164.A boundary line 164A between the sections 163 and 164 represents a protuberant portion on the ferrite substrate surface.
The Sendust film formed on the ferrite substrate having recesses and protuberances present different directions of columnar crystal growth with the inclination of the recesses. Thus the direction and size of the columnar crystals differ with the profile and inclination of the bottom of the substrate recess.
The Sendust film surface 162 is also disturbed and the crystal structure of the film differs markedly with different inclination on the bottom of the recess.
Such differences in the crystal grain structure account for a great difference in the magnetic permeability of the Sendust film. The photograph in this figure is again upside down.
It should be noted that, because magnetic permeability as well as anisotropic properties (the direction of easy magnetization) of a ferromagnetic film depends substantially on the film structure, it is desirable that the magnetic film that makes up a magnetic transducer head, especially one used for magnetic recording and reproduction, be uniform in structure. For instance, it is required that columnar crystals of the aforementioned Sendust film should grow uniformly and in one direction. Should the orientation of crystal growth not be uniform in a magnetic film, a certain portion of the film exhibits proper magnetic properties while the remaining portion thereof exhibits inferior magnetic properties (effect of anisotropy).
In Figure 6 of the accompanying drawings, there is schematically shown the structure of a Sendust film, that is, the orientation of the columnar crystal growths, when the Sendust film is deposited as by sputtering on and astride the projecting portion of the ferriate substrate shown in Figure 3. It is seen from Figrure 6 that columnar crystals of the Sendust film 171 grow uniformly and parallel to each other on both sides 170A of the projecting portion 170 but are spread apart from each other towards the distal ends at a free end 170B. When the Sendust film 171 deposited on the free end 170B is ground for forming a magnetic gap surface 172, the film structure at or near the gap surface 172 is different from that on the sides 170A.Thus, with the magnetic transducer head of the composite magnetic material making use of the Sendustfilm 171 deposited on the projecting portion 170, when the Sendust film 171 on the sides 170A exhibits higher magnetic permeability in the direction of the path of magnetic flux, the film 171 near the free end 170B exhibits only poor magnetic permeability.
Instead of depositing, for instance, a Sendust film on and astride the projecting portion of the ferrite substrate, it is also feasible to deposit the Sendust film 177 only on one side of the projecting portion 175, as by sputtering, with a masking plate 176 placed to cover the other side of the projecting portion 175. However, the masking plate 176 gives rise to a shadowing effect because a plate thickness in excess of several tens of microns is required in consideration of handling and mask-alignment and by reason of moulding constraints. As a result of the shadowing effet, the film structure of the Sendust film 177 formed in the vicinity ofthe free end 175B of the projecting portion 175B and hence the magnetic permeability characteristics are different from those of the film structure on the side 175A. Thus, when the Sendust film 177 deposited on the free end 175B is ground to a magnetic gap surface 178 of the magnetic transducer head, it is not possible with this magnetic head to provide the film portion on the free end 175B and the film portion on the side 175A with high magnetic permeability along the path of magnetic flux.
It is also feasible to get the gap surface ground further so asto renderthefilm structure atthefree end 175B of the Sendust film identical with that at the side 175A. However, in this case, the ferrite portion is exposed on the magnetic gap surface 179 of the magnetic head, with the resulting inconvenience that a sufficient magnetic recording cannot be obtained on the track portions of the high coercive force magnetic tape, such as metal tape, correspond- ing to the width of the exposed ferrite portion.
Figures 11 and 12 of the accompanying drawings show in plan views two further examples of the contact surface with the tape of the previously proposed magnetic heads, with the magnetic gap portion being shown on an enlarged scale. With the magnetic head shown in Figure 11, the Sendust films 183 for example are provided only on both sides of the ferrite portions projecting towards the planar surface 180 forming the gap and the ferrite portion is exposed on the planar surface 180 forming the gap.
The numerals 184 designates a reinforcing glass packing material. This magnetic transducer head makes use of the Sendust film 183 formed on the planar surface and hence does not suffer from the above described non-uniform film structure. However, the magnetic recording on a high coercive force magnetic tape is insufficient by a width of the ferrite portion exposed on the magnetic gap surface, and the magnetic recording characteristics and playback output is corresponding lowered.
In the magnetic transducer head shown in Figure 12, a Sendust film 187, for example, is formed on ferrite portions and non-magnetic glass having high melting point portions 188 or core elements 185 and 186, so thatthe head is formed of composite magnetic material, such as ferrite and Sendust. The numeral 190 designates glass having a melting point lower than that of glass 188. The magnetic gap 189 of the magnetic transducer head is formed by the portions of the Sendust film 187A running parallel to the path of magnetic flux, so that the Sendust film 187A in the vicinity of the magnetic gap 189 is of a uniform film structure.However, the Sendust film portion 187B corresponding to the bend or knee of the Sendust film 187 and thus extending over two planar surfaces is not of uniform film structure, so that the Sendustfilm 187 as a whole is not constant in magnetic permeability. Also, in this magnetic transducer head, the Sendust film portion 187A needs to be of a film thickness corresponding to the track width. Because of the slow deposition rate of the film possible with the physical vapour deposition, the process of fabrication of the magnetic transducer head is time-consuming.
Japanese Patent Kokai No. 56/169214 shows a magnetic transducer head in which, as shown in Figure 13 of the accompanying drawings, junction surfaces 195 and 196 of magnetic alloy films 191 and 192 and ferrite portions 193 and 194 are at an acute angle with respect to the confronting surfaces of the head gap 197 or to a direction normal to the relative running direction of the magnetic recording medium. However, with the magnetic transducer head shown in Figure 13, the magnetic alloy films 191 and 192 are mounted in opposition to each other in other portions than the head gap 197, so that cross-talk may be caused especially in a longer wavelength signal by picking up the signals of neighbouring tracks or the signals of every other track, and a means for avoiding this effectively has not been found to date.In addition, local wear may be caused by the head gap 197 being offset to one side of the head chip. The magnetic alloy films 191 and 192 abut on each other in such a manner that the direction of columnar crystal growth ofthefilm 191 does not coincide with that of the film 192, and uniform magnetic properties are difficult to achieve with the head gap 197.
Although the crystalline Sendust film has been given hereinabove as an example of a thin ferro magnetic film, a uniform film structure is also required when an amorphous alloy is used for forming the thin film. Since the film is amorphous, it is not the uniformity in the crystal grain structure but the uniformity in the magnetic anisotropy that matters. If the amorphous alloy is deposited on a planar surface for forming a thin film, magnetic anisotropy is identical throughhout the film. However, when the alloy is deposited astride a projecting portion and a planar portion, the magnetic domain structure or the magnetic permeability is not uniform.
According to the present invention there is provided a magnetic transducer head comprising: a first magnetic core element; and a second magnetic core element; each of said first and second core elements comprising a magnetic ferrite block and a magnetic metal thin film integrated with said magnetic ferrite block; each of said first and second core elements having a first planar surface and a second planar surface; said magnetic metal thin film being provided on said second planar surface and facing an edge thereof to said first planar surface, said second planar surface being inclined with respect to said first planar surface; and said first and second core element being bonded together in such manner that an operating magnetic gap is formed between said edge of said magnetic metal thin film on said first core element and said edge of said magnetic metal thin film on said second core element, said magnetic metal thin film on said second core element are in one common plane, and a common contact surface to face a travelling magnetic recording medium is formed by said first and second core elements.
According to the present invention there is also provided a magnetic transducer head comprising: a first and a second magnetic core element bonded together and having an operating magnetic gap between first surfaces of each of said magnetic core elements and a contact surface to face a travelling magnetic recording medium, said gap extending substantially perpendicular to said contact surface forming a depth of said operating magnetic gap; each of said magnetic core elements being formed of a magnetic ferrite block, and a magnetic metal thin film formed on a second surface of said magnetic ferrite block; ; said magnetic metal thin film being provided in such manner that an edge of said magnetic metal thin film appearing on said first surface of said magnetic core element extends parallel to a direction of said depth, and another edge appearing on said contact surface extends along a line having an angle not equal to a right angle to said operating magnetic gap as viewed on said contact surface; and said core elements being bonded together in such manner that said operating magnetic gap is formed between said edges appearing on said first surface of each of said magnetic core elements, and said other edges align in a common straight line.
According to the present invention there is also provided 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 on 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 cut-out portion extending from said first planar surface adjacent to said magnetic metal thin film, said contact surface and another surface extending adjacent to said first planar surface and said contact surface; 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.
According to the present invention there is also provided a magnetic transducer head comprising: a pair of magnetic core elements bonded to form an operating magnetic gap therebetween and forming a contact surface for a travelling magnetic recording medium; said operating magnetic gap being formed between magnetic metal thin films each formed in said magnetic core elements and said magnetic metal thin films extending on said contact surface along a straight line having an angle not equal to a right angle to said operating magnetic gap; said magnetic metal thin films having substantially uniform columnar grain structure over the entire area of said magnetic metal thin films.
According to the present invention there is also provided a magnetic transducer head comprising: a pair of magnetic core elements, being bonded to form an operating magnetic gap therebetween and forming a contact surface for a travelling magnetic recording medium; said operating magnetic gap being formed between magnetic metal thin films each formed in said magnetic core elements, and said magnetic metal thin films extending on said contact surface along a straight line having an angle not equal to a right angle to said operating magnetic gap; said magnetic metal thin film having substantially uniform characteristics of magnetic anisotropy over the entire area of said magnetic metal thin film.
According to the present invention there is also provided a method of manufacturing a magnetic transducer head comprising the steps of: preparing a pair of magnetic ferrite blocks each having a first and a second surface adjacent to each other; forming a first groove over a corner of said first and said second surface extending to said first and said second surfaces; forming a second groove over said corner and adjacent to said first groove, said second groove having a third surface adjacent to said first groove and extending slantingly with respectto said second surface, a line formed by said second surface and said third surface being extended perpendicular to said first surface; forming magnetic metal thin film over said surface by physical vapour deposition; polishing a side of said second surface to expose an edge of said magnetic metal thin film;; forming a third groove for winding a coil on at least one of said ferrite blocks; and bonding said ferrite blocks to form a magnetic gap between said edges of said magnetic metal thin film formed on said ferrite blocks.
The invention will now be described by way of example with reference to the accompanying drawings, throughoutwhich like parts are referred to by like references, and in which: Figures 1 and 2 are perspective views showing two examples of previously proposed magnetic transducer heads: Figure 3 is a plan view showing on an enlarged scale the tape contacting surface of a previously proposed magnetic head; Figure 4A is a SEM photograph showing a crystalline structure of the two-layered Sendust film formed by sputtering on a planar ferrite substrate surface; Figure 4B is a sketch showing only the outstanding features of the SEM photograph of Figure 4A; Figure 5A is an SEM photograph showing a crystalline structure of the Sendust film formed by sputtering on an irregular ferrite substrate surface;; Figure 5B is a sketch showing only the outstanding features of the SEM photograph of Figure 5A; Figures 6to 10 are schematic sectional views showing the manufacturing process of a previously proposed magnetic transducer head and particularly the orientation of the columnar crystal growths of, for example, the Sendust film formed on projecting ferrite portions; Figures 11 and 12 are enlarged plan views showing contact surfaces with the tape of the previously proposed magnetic transducer heads; Figure 13 is an enlarged plan view showing the contact surface with the tape of a further conventional magnetic transducer head; Figure 14 is a perspective view showing an embodiment of magnetic transducer head according to the present invention;; Figure 15 ís an enlarged plan view showing the contact surface with the tape of the magnetic transducer head shown in Figure 14; Figure 16 is an exploded perspective view of the head shown in Figure 14, with the explosion being on the core separation plane; Figures 17to 23 are perspective views showing the sequential steps for fabrication of the magnetic transducer head shown in Figure 14; Figures 24 and 25 are schematic sectional views showing the orientation of the columnar crystal growth of the ferromagnetic metal film (Fe-Al-Si alloys film) formed on the substrate at the process steps shown in Figures 20 and 21, respectively; Figure 26 is a perspective view showing a modified groove profile for the step shown in Figure 17;; Figure 27 is an enlarged plan view of the contact surface with the tape of the magnetic transducer head when the groove profile as shown in Figure 26 is employed; Figures 28to 30 are enlarged plan views of the contact surface with the tape of the modified magnetic transducer head shown in Figure 26; Figure 31 is a perspective view of a modified embodiment of magnetic transducer head; Figure 32 is an enlarged plan view showing the contact surface with the tape of the magnetic transducer head shown in Figure 26; Figures 33 to 39 are perspective views showing the sequential steps for the manufacture of the magnetic transducer head shown in Figure 31;; Figures 40 and 41 are schematic sectional views showing the orientation of the columnar crystal growth of the ferromagnetic metal film (Fe-Al-Si alloys film) formed on the substrate at the process steps shown in Figures 36 and 37, respectively; Figures 42 to 48 are perspective views showing the sequential steps for the manufacture of another modified embodiment of magnetic transducer head; and Figure 49 is a perspective view showing a magnetic transducer head manufactured by the process steps shown in Figures 42 to 48, respectively.
Referring first to Figure 14, a magnetic transducer head according to the first embodiment of the present invention will be explained, in which a ferromagnetic metal thin film film is formed continuously from the front side or the front gap forming surface to the back side or the back gap forming surface of the magnetic transducer head.
This head is composed of core elements 80 and 81 formed of ferromagnetic oxides, such as Mn-Zn ferrite. On the junction surfaces of the core elements 80 and 81, there are formed metal thin films 82 of ferromagnetic metal or high permeability metal alloy, such as Fe-Al-Si alloys, by using physical vapour deposition, such as sputtering. The films 82 are continuously formed from the front gap forming surface to the rear gap forming surface. A magnetic gap g is formed only by the thin films 82. The thin films 82 on the core elements 80 and 81 extend as an oblique straight line when viewed on the tape contact surface, if the small thickness of the thin films 82 is disregarded. The reinforcing nonmagnetic sections 83 and 84 fill cut-out portions adjacent to the junction surface, and also a track width Tw. An opening 85 is provided for coils.
The thin films 82 are formed on a sole planar surface defined by one inclined surface 80A of the core element 80 and one inclined surface 81A of the core element 81. Therefore, the thin films 82 are of uniform film stucture in their entirety and exhibit a high magnetic permeability in the direction of the path of magnetic flux for improving the recording characteristics and increasing playback output of the magnetic transducer head.
The surface for forming the thin films 82 forms an acute angle 0 with the surface for forming the magnetic gap g, as shown in Figure 15 showing the contact surface with the magnetic tape in a plan view. In the present embodiment, the angle 6 is selected to be a relatively small value of approxi mately 45", so that the interaction of the magnetic gap g with the interface between the inclined surfaces 80A and 81A and the thin films 82 is negligible.
The deposited metal thin films 82 need only to be of a film thickness such that t = Tw sin 6 wherein Tw represents the track width and 6 represents the angle between the surface for forming the metal thin film and the surface for forming the magnetic gap. 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 significantly reduced.
It should be noted that the angle 6 of 45 between the surface for forming the films 82 and the surface for forming the magnetic gap g is not limitative and may also be in the range from about 20 to about 80 However, an angle of more than 30 is preferred because cross-talk with the neighbouring track is increased with the angle 6 than 20 . The angle 6 less than about 80 is preferred because wear resistance is lowered with the angle equal to 90 . The angle 6 to 90 also is not preferred because the thickness of the thin films 82 of the ferromagnetic metal need to be equal to the track width which gives rise to a non-uniform film structure and a time-consuming operation in forming the thin film in vacuum, as described hereinabove.
The metal thin films 82 may be formed of the ferromagnetic metals including Fe-Al-Si alloys, Fe-Al alloys, Fe-Si alloys, Fe-Si-Co alloys, Ni-Fe alloys (so-called permalloys), ferromagnetic amorphous metal alloys, or so-called amorphous alloys, such as metal-metalloid amorphous alloys, for example an alloy of one or more elements selected from the group of Fe, Ni and Co with one or more elements selected from the group P, C, B and Si, or an alloy comprising the firstly mentioned alloy and containing Al, Fe, Be, Sn, In, Mo, W, Ti, Mn, Cr, Zr, Hf or Nb, or a metal-metal amorphous alloy comprising transition metal elements and glass forming metal elements such as Hf or Zr.
Preferably, the composition of the Fe-Al-Si alloys is so selected that the Al contents are in the range from 2 to 10 weight percent, and the Si contents are in the range from 4 to 15 weight percent, the balance being Fe. Thus it is preferred that, when the Fe-Al-Si alloys are expressed as FeaAlbSic where a, b and c represent the weight ratio of the respective associated components, and the values of a,b and care in the range such that: 70 ' a I 95 2 # b # 10 4#c#15 If the Al or Si contents are too low or too high, the magnetic properties of the Fe-Al-Si alloys are impaired.
In the above composition, some of the Fe may be replaced by at least one of Co and Ni.
The saturation magnetic flux density may be improved by replacing some of the Fe with Co.
Above all, the maximum saturation magnetic flux density Bs may be achieved when 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 some of the Fe with Ni, the magnetic permeability may be maintained at a higher value without lowering the saturation magnetic flux density Bs. In this case, the amount of Ni is preferably in the range from 0 to 40 weight percent relative to the Fe.
Other elements may also be added to the Fe-Al-Si alloys for improving its corrosion and wear resistance. The elements that may be used as such additives include Illa group elements including lanthanides such as Sc, Y, La, Ce, Nd and Gd; IVa group elements such as Ti, Zr or Hf; Va groups such as V, Nb or Ta; Vla group elements such as Cr, Mo or W; Vlla group elements such as Mn, Te or Re; Ib group elements such as Cu, Ag or Au elements of the platinum group as Ru, Rh, Pd, and Ga, In, Ge, Sn, Sb or Bi.
As the film forming process, any known physical vapour deposition may be employed, such as flash evaporation, ion plating, sputtering or a cluster ion beam process.
It is known that, in producing the above described thin film of a ferromagnetic metal by, for example, sputtering, a columnar structure is induced in a thin film of a ferromagnetic metal obtained under a certain condition and thus a thin film with excellent magnetic properties may be obtained. Above all, when the thin film of the ferromagnetic metal is designed to be used in a composite magnetic head, it is generally thought that, for suppressing the anisotropy of the formed film, it would be more preferred to induce the growth of the columnar structure at right angles to the substrate surface on which the film is formed.
However, with the ferromagnetic metal thin film obtained in this manner, that is, with the columnar structure caused to grow at right angles to the substrate surface, the slightest changes in sputtering conditions or substrate position delicately affect the growth of the columnar structure, so that the resulting thin film is changed in magnetic permeability with resulting dispersion in the playback output of the magnetic transducer head.
It is therefore preferred that the metal thin films 82 be deposited in such a manner that the direction of the columnar crystal growths be inclined at a predetermined angle A of 5 to 45 with respect to a normal line drawn to each of the inclined planar surfaces 80A and 81A.
When the metal thin films 82 are caused to grow in this manner at a predetermined angle A with respect to the normal lines drawn to the inclined surfaces 80A and 81A, the magnetic properties of the resulting ferromagnetic metal thin films 82 are stable and superior, resulting in improved magnetic properties of the magnetic transducer head.
The angle of direction of the columnar crystal growths of the metal thin films 82 makes with the normal direction to the inclined surfaces 80a and 81 A is preferably in the range of 5 to 45 for best results.
When the angle X is less than 5 , the playback output of the magnetic transducer head is greatly fluctuated thus resulting in a lower yield rate and elevated costs. When the angle X is more than 45 , the magnetic properties of the thin films 82 are drastically affected by considerable depletion between the columnar crystals and surface ruggedness thus causing the playback output of the magnetic transducer head to be lowered. With the angle X in the range from 5 to 45% the growth of the columnar crystals is fixed because of the oblique incidence, and the magnetic properties are not changed markedly with small fluctuations in the sputtering conditions or difference in the substrate position.
The alternating condensation and rarefaction between or within the columnar crystals induced by oblique growths disperse the strain caused during sputtering,film annealing and the working ofthe head, so that the playback output is increased while the output fluctuations are less than about 2 d B.
As a means of regulating the direction of growth of the ferromagnetic metal thin film 82, the substrate surface may be inclined with respect to an evaporation source, or the substrate may be placed around the evaporation source so that vaporized magnetic particles coming from an oblique direction may be deposited on the substrate.
Although the metal thin film 82 is formed as a single layer by the above described physical vapour deposition, a plurality of thin metal layers may also be formed with an electrically insulating film or films such as S102, Ta205, Awl203, ZrO2 or Si3N4 between the adjacent thin metal layers. Any desired number of the ferromagnetic metal layers may be used for the formation of the metal thin film.
Since the magnetic gap g is formed only by the metal thin films 82 endowed with high magnetic permeability, the magnetic transducer head has a high recording characteristic and playback output compatible with the magnetic tape exhibiting high coercive force Hc, such as metal tape.
Since the metal thin films 82 are formed on a common planar surface such as the inclined surface 80A of the projecting portion of the core element 80 or the inclined surface 81A of the projecting portion, the film structure of the metal thin film 82 (Fe-Al-Si alloys film), that is, the orientation of the columnar crystal growths is uniform and parallel not only in the neighbourhood of the magnetic gap g but on the overall surface of the inclined surfaces 80A and 81A.
The result is that the metal thin film 82 shows high magnetic permeability in its entirety along the path of magnetic flux for improving the recording characteristics and increasing playback output of the magnetic transducer head.
The contact surface with the tape of the magnetic transducer head is substantially formed of ferromagnetic oxides, so the wear resistance of the head is also improved.
In distinction from the conventional practice according to which ferromagnetic metal foils are manually applied with the aid of glass, organic adhesives or inorganic adhesives, the metal thin films 82 are provided by physical vapour deposition, so that the films are more homogenous and the operational reliability of the transducer head is also improved.
Track widths in the range from several tens of microns can be formed easily, and a narrow track may be provided to the head by reducing the number of layers or film thickness of the metal thin film 82.
The magnetic transducer head described hereinabove may be used advantageously for high density recording on a magnetic tape with high coercive force Hc by virtue of the high magnetic field strength of the magnetic gap g and the structure playback output.
For clarifying the structure of the magnetic transducer head of the present embodiment, the manufacture process thereof will be explained below by referring to Figures 17 to 23.
In preparing the magnetic transducer head of the present embodiment, a plurality of vee grooves 91 are transversely formed on the upper surface of a substrate 90 of ferromagnetic oxide, such as Mn-Zn ferrite, with the aid of a revolving grindstone (Figure 17).
The grooves 91 may also be polygonal in crosssection and the inner wall surface of the grooves 91 may be bent in two or more steps for enlarging the distance between the ferromagnetic oxides and the ferromagnetic metal thin film. With such a groove profile, high-output magnetic transducer heads with less cross-talk may be obtained in the longer wavelength range while maintaining a large junction area between the ferromagnetic oxide on one core half and the ferromagnetic metal thin film on another core half.
The profile of the groove 91 as shown in Figure 26 may be used as an example. The contact surface with the tape of the resulting magnetic head is as shown in Figure 27 wherein end faces 80B and 81 B of the track width regulating grooves of the core elements 80 and 81 are bent in two steps so as to be in register with the profile of the groove 91, that is, with a portion of the inner wall surface of a polygon.
Therefore, some distance between the end faces 80B and 81 B of the track width regulating grooves and the ferromagnetic metal thin films 82 may be procured and the cross-talk components resulting from reproduction of the long wavelength components may be lowered.
In addition, the end face portions 80B, and 80B2 or 81 B, and 81 B2 that make up the end faces 80B and 81 B of the track width regulating groves are inclined at different angles from the azimuth angle of the magnetic gap g, so that cross-talk with adjacent and adjacent but one tracks is lowered.
In general, means are employed to lower the cross-talk between the adjacent tracks to a negligible level, for instance, recording the neighbouring tracks with different azimuth angles for removing the effect of cross-talk (as in magnetic tape in a VTR). However, the cross-talk is caused between every other track having the same azimuth angle. In the present embodiment, the end faces 80B and 81 B of the track width regulating grooves of the core elements 80 and 81 are inclined in two steps at different angles from the azimuth angle of the magnetic gap g so that, even the edges of the end face portions 80B1, 80B2, 81 B, and 81 B2 of the core elements 80 and 81 are in register with every neighbouring track or every track, signal pick-up from every neighbouring track or every other tracks or cross-talk may be lowered by azimuth loss.
Figures 28, 29 and 30 show in plan views the contact surface with the tape of modified embodiments wherein the groove 91 is changed in profile. In these modifications, the end faces 80B and 81 B of the track width regulating grooves on both sides of the magnetic gap g are changed in profile. In the embodiment shown in Figure 28, the end faces 80B and81B ofthetrackwidth regulating grooves formed on core elements 80 and 81 are formed as gently sloped surfaces with knees 80B1, 80B2, 81 B, and 81 B2. In the embodiment shown in Figure 29, the end faces SOB and 81 B of the track width regulating grooves on the core elements 80 and 81 are formed as surfaces with knees 80elm 80B2, 81 B, and 81 B2 with larger radii of curvature at the knees.In the embodiment shown in Figure 30, the end faces SOB and 81 B of the track width regulating grooves on the core elements 80 and 81 are formed as surfaces with double knees SOB1, 80B2, 80B3, 81 by, 81 B2 and 81 B3.
The end faces of the track width regulating grooves may also be modified in such a manner that the inclined surface with a knee has different tilts in the respective segments divided by the knee, or the inclined surface has more than three knees.
Next, glass 92 having a high melting point is filled in a molten state in the grooves 91, after which the substrate surface is ground smooth (Figure 18).
Next, a plurality of vee grooves 93 are formed so as to be adjacent to and not to overlap with the aforementioned vee grooves 91. The inner wall surface of each groove 93 makes an angle of, for example, 45 with respect to the upper substrate surface (Figure 19).
Then a ferromagnetic alloy, such as Fe-Al-Si alloy, is deposited on the upper surface of the substrate 90 by any known physical vapour deposition such as sputtering, ion plating or vacuum evaporation, thereby forming a metal thin film 94 in the vee grooves 93 (Figure 20).
Then the upper and front surfaces of the substrate 90 are ground smooth and removing the metal thin film on the surface of the substrate (Figure 21).
For forming the core element on the winding groove side, a groove 95 for coils in the resulting magnetic transducer head and a glass filling groove 96 are cut on the thus processed substrate 90 (Figure 21) for providing a substrate 97 formed of ferromagnetic oxide (Figure 22).
The substrates 90 and 97 are then stacked together by placing a gap spacer therebetween and with the respective planar surfaces provided with the metal thin films 94 facing each other. Low melting glass rods are inserted into the coil groove 95 and the glass filling groove 96 for meltbonding the substrates together with one block 98. At this time, glass 99 having a low melting point is filled into the remaining grooves on the metal thin films 94 of the substrates 90 and 97 (Figure 23).
The block 98 is then cut along lines b-b and b'-b' for providing a plurality of the head chips.
The contact surface of each head chip with the magnetic tape is then ground to a cylindrical profile for producing the magnetic transducer head shown in Figure 14. This magnetic transducer head has its core element 80 derived from the substrate 90 and another core element 81 derived from the substrate 90, and another core element 81 derived from the substrate 97. The metal thin film 82 corresponds to the metal thin film 94, the non-magnetic filling material 83 to the glass 92 having high a melting point and the non-magnetic filling material to the glass 99 having a lower melting point. The coil opening 85 corresponds to the coil groove 95.
In Figures 24 and 25, sections through the substrate 90 are taken at the steps shown in Figures 20 and 21, respectively, for illustrating the film structure of the metal thin film 94 (Fe-Al-Si alloys film) or the orientation of the columnar crystal growths. As shown in these figures, a non-uniform film structure portion R is ground off during the gap surface grinding step shown in Figure 21. so that only the metal thin film 94 having a uniform film structure is left on the inclined surface of the groove 93. The result is that the magnetic transducer head having a high and stable output may be obtained because each portion of the metal thin film 82 formed on the common planar surface may have a high permeability along the path of the magnetic flux.
A modified embodiment in which the ferromagnetic metal thin film is formed only in the vicinity of the magnetic gap is hereafter explained.
Figure 31 shows in perspective the magnetic transducer head according to the present modification. The magnetic transducer head is formed of a composite magnetic material and comprises a pair of core elements 10 and 11 of ferromagnetic oxides such as Mn-Zn ferrite. In the vicinity of the magnetic gap g, there are formed metal thin films 14A and 14B of ferromagnetic metal or high permeability metal alloy, such as Fe-Al-Si alloys, by using physical vapour deposition, such as sputtering. Nonmagnetic packing materials 12A, 12B and 13 are packed in molten state in the neighbourhood of the planar surface of the magnetic gap g.
It should be noted that the planar surface forming the metal thin films 14A and 14B and the planar surface forming the magnetic gap g are inclined to each other at an angle 6 as shown in Figure 32 showing the contact surface with the tape of the magnetic transducer head. In the present embodiment, the angle 6 is approximately 450 Since the metal thin films 14a and 14B are formed only in the vicinity of the magnetic gap g, the film surface may be reduced with the result that the number of unit chips that can be processed at a time by, for example, sputtering can be notably increased with improved efficiency in mass production. With increase in the number of magnetic transducer heads that can be produced from a unit film area, manufacturing costs of the magnetic transducer heads may be lowered.
On account of the reduced area of the metal thin films 14A and 14B on the core elements 10 and 11 of the ferromagnetic oxides, any strain of the metal thin films 14A and 14B caused by the difference in the coefficients of thermal expansion of the core elements and the metal thin films or resulting breaks or cracks occurring in the core elements 10 and 11 may be avoided, with improved operational efficiency and yield rate in the manufacture of the magnetic transducer heads.
The metal thin films 14A and 14B of high magnetic permeability defining the magnetic gap g are formed in the vicinity of the magnetic gap g, and the rear side of the head is formed by ferromagnetic oxides with a large junction surface, so that the head exhibits an improved performance with lesser magnetic reluctance and high sensitivity.
Since the magnetic gap g is formed only by the ferromagnetic metal thin films 14A and 14B of high magnetic permeability, the head has high recording characteristics and a playback output compatible with magnetic tapes of high coercive force such as metal tape.
The metal thin film 14A is formed on a planar surface on the non-magnetic packing material 12A and the side 1 OA of the projecting portion of the core element 10, while the metal thin film 14B is formed on a planar surface on the non-magnetic packing material 12B and the side 11 A of the projecting portion of the core element 11. Hence, the film structure of the orientation of the columnar crystal growths of the metal (Fe-Al-Si alloys) thin films 14A and 14B is uniform and parallel both in the neighbourhood of the magnetic gap g and on the sides 1 OA and 1 A. The result is that the metal thin films 14A and 14B exhibit in their entirety a high magnetic permeability in the direction of the path of magnetic flux so that the recording characteristics and playback output of the magnetic transducer head is substantially improved.
The rear sides of the magnetic transducer head are united together with the ferromagnetic oxides such as Mn-Zn ferrite abutting to each other so that a large bonding strength may be achieved with improved yield rate despite inferior bonding properties between the metal thin films 14A and 14B and the core elements 10 and 11. There is no risk of back track deviation being caused during processing, thus resulting in an improved operational reliability of the magnetic transducer head.
Since most of the contact surface with the tape of the magnetic transducer head is formed of ferromagnetic oxides, the wear resistance of the magnetic transducer head is also improved.
In distinction from the conventional practice in which ferromagnetic metal foils are manually bonded one upon the other with an adhesive layer of glass, organic adhesives or inorganic adhesives, the metal thin films 14A and 14B are formed by a physical vapour deposition, so that the formed film is homogenous for further improving the operational reliability of the magnetic transducer head.
The track width can be easily selected in a wide range from several to several tens of microns, so that a magnetic transducer head with a narrow track width may be obtained by using a reduced film thickness or a reduced number of film layers.
As described hereinabove, the magnetic transducer head of the present embodiment has a high magnetic field strength of the magnetic gap g and a high playback output, so that it is superior in operational reliability and productivity, and suitable for high density recording on a magnetic tape having a high coercive force Hc such as metal tape.
The manufacture process for the magnetic transducer head shown in Figure 31 will now be explained by referring to Figures 33 to 39.
On a longitudinal ridge of a substrate 20 of a ferromagnetic oxide, such as Mn-Zn ferrite, a plurality of dihedral recesses 21 are cut with the aid of a revolving grindstone or by electrolytic etching (Figure 33). The upper side or surface 23 of the substrate 20 corresponds to the magnetic gap forming surface, and the recess 21 is formed at a portion of the substrate 20 where the magnetic gap is to be formed. The recess 21 may also be polyhedral and provided with curved portions, as in the preceding embodiment.
Glass having high melting point is packed in molten state in the recess 21 at 22A and both the upper side 23 and the front side 24 are ground smooth (Figure 34).
On the same ridge 25 are then formed a second plurality of dihedral recesses 25 adjacent to the recesses 21 filled with glass packing 22A and so as to be partially overlapped with the recess 21 (Figure 35). A part of the glass packing 22A is exposed on an inner wall side or facet 26 of the recess 25. A line of intersection 27 of the wall side 26 and the upper side 23 forms a right angle with the front side 24, while the inner wall side 26 makes an angle of say 45 with the upper side 23.
Next, a high permeability alloy such as a Fe-Al-Si alloy is deposited in the neighbourhood of the recesses 25 of the substrate 20 with the intermediary of an insulating film with the aid of physical vapour deposition such as sputtering for forming a ferromagnetic metal thin film 28 (Figure 36). The substrate 20 is placed at this time in the sputtering apparatus at an inclined position for more efficient depositing of the inner wall sides 26.
Then a glass packing 29 having a melting point lower than that of the glass packing 22 is packed in the molten state in the recesses 25 provided with the metal thin film 28, after which the upper side 23 and the front side 24 are ground to a mirror finish (Figure 37). At this time, a part of the metal thin film 28 deposited during the preceding step remains on the wall sides 26 of the recesses 25, so that the ferromagnetic metal thin films 28A are deposited on the sides 26.
For forming a winding groove side core element, a groove 31 for coils is formed in the substrate 20 of ferromagnetic oxides shown in Figure 32 for providing a substrate 30 of ferromagnetic oxides shown in Figure 38. The recesses 21 of the substrate shown in Figure 38 are filled with glass 22B having a high melting point, in the molten state, while the inner wall sides of the recesses 25 are provided with ferromagnetic metal thin films 28B.
The substrates 20 and 30 are stacked and bonded together with molten glass, with the upper side 23 or the magnetic gap forming surface of the substrate 20 abutting on the upper side 32 or the magnetic gap forming surface of the substrate 30 with the medium of a gap spacer (Figure 39) for providing a block 33 consisting of the substrates 20 and 30. The block 33 is then sliced along lines a-a, a'-a' for forming a plurality of head chips. The gap spacer may be formed of SiO2, ZrO2, Ta205 or Cr, as desired.
The contact surface with the tape of the head chip is then subjected to cylindrical grinding for forming a magnetic transducer head as shown in Figure 31.
The core elements 10 and 11 of the magnetic transducer head shown in Figure 31 are derived from the substrates 20 and 30, respectively. The nonmagnetic packing materials 12A and 12B correspond to the glass packing materials having a high melting point 22A and 22B, respectively, while the nonmagnetic packing material 13 corresponds to the glass packing material having a low melting point 13. The ferromagnetic metal thin films 14A and 14B of the magnetic transducer head correspond to the metal thin films 28A and 28B, while the coil opening 15 corresponds to the coil groove 31 on the substrate.
In the above described magnetic transducer head, a portion Q of the metal thin film 28 of the non-uniform film structure formed during the process step shown in Figure 36 is removed by the grinding operation of the gap surface, as schematically shown in Figures 40 and 41 showing the orientation of columnar crystal growths or film structure of the ferromagnetic metal thin film, for example, the Fe-Al-Si alloy film. In this manner, only the metal thin films 28A and 28B of uniform structure are left on a sole inclined planar surface which is the inner wall side of facet 26 of the recess 25. The result is that each portion of the metal thin films 28A and 28B exhibits high magnetic permeability along the path of magnetic flux and the magnetic transducer head has a high and stable playback output.
In the present embodiment, as described hereinabove, a second planar surface forming an angle of 200 to 800 with respect to a first planar surface which later forms the magnetic gap surface is formed by the grinding process and in the neighbourhood of the first recess 21 filled previously with glass having a high melting point, and the ferromagnetic metal thin film 28 is formed by a physical vapour deposition on said second surface which is inclined with respect to said first planar surface, which is then ground so that only the thin film formed on the inclined second planar surface is left at least in the vicinity on the magnetic gap. The result is that the metal thin films 28A and 28B are of uniform film structure throughout thus providing for a high and stable output of the magnetic transducer head.
With the above magnetic transducer head, the ferromagnetic oxides of the two core elements are melt-bonded together directly with molten glass on the rear junction sides or back gap surfaces of the head. The result is that the head chip shows an improved breaking strength and can be manufactured easily with an improved yield rate.
Referring to Figures 42 to 48, a further example of the magnetic transducer head manufactured by a further process will be explained.
On an upper surface 41 corresponding to the contact surface with the tape of the substrate 40 of ferromagnetic oxides, such as Mn-Zn ferrite, a plurality of grooves 42 having the square shaped section are obliquely formed (Figure 42). Each groove 42 has a depth to reach the coil opening provided in the transducer head.
Glass having a high melting point is then packed in molten state at 43A in each groove 42, after which the upper side 41 and the front side 44 are ground smooth (Figure 43).
Then, a second plurality of grooves 45 having the square shaped section are formed on the upper side 41 in the reverse oblique direction to the grooves 42 so as partially to overlap with the grooves 42 filled with glass 43A having a high melting point (Figure 44). The grooves 45 are approximately equal in depth to the glass-packed grooves 42. The line of intersection 47 which the inner side 46 of the groove 45 makes with the front side 44 is situated on the sectional plane of the glass 43A exposed on the front side 44 and forms a right angle with the upper side 41. The inner side 46 makes an angle of, say, 45 with the front side 44.
Then, a film of high permeability alloy, such as Fe-Al-Si alloy, is formed in the vicinity of the grooves 44 on the substrate 40 by physical vapour deposition, such as sputtering, for forming a ferromagnetic metal thin film 48 (Figure 45). The substrate 40 is maintained at an inclined position within the sputtering apparatus for more efficient forming of the film on the inner side 46.
Then, glass 49 having a lower melting pointthan the glass 43A is packed in molten state in the grooves 45 provided with the metal thin film 48, after which the upper and front sides 41 and 44 are ground to a mirror finish (Figure 46). At this time, a part of the metal thin film 48 is left on the inner sides 46 of the grooves 45 so that the ferromagnetic metal thin film 48A is provided on these inner sides 46.
For forming the core element provided with a groove for coils 61, the groove 61 is formed on the substrate 40 of ferromagnetic oxides as shown in Figure 46 for producing the substrate 60 of ferromagnetic oxides as shown in Figure 47. The grooves 42 of the substrate 60 are packed with glass 43B having a high melting point in molten state, while the ferromagnetic metal thin films 48B are formed on the inner sides 46 of the grooves 45.
The substrates 40 and 60 are then stacked and bonded together by molten glass with the front side 44 of the substrate 40 which later forms the magnetic gap abutting on the front side 62 of the substrate 60 which later forms the gap by the medium of a gap spacer (Figure 48) for providing a block 63 consisting of the substrated 40 and 60. The block 63 is then sliced along lines A-A, A'-A' for forming a plurality of head chips.
The contact surface with the magnetic tape of the head chip is then subjected to cylindrical processing for forming a magnetic transducer head shown in Figure 49. The core elements 70 and 71 of the magnetic transducer head shown in Figure 49 are derived from the substrates 40 and 60, respectively.
The non-magnetic packing materials 72A and 72B correspond to the glass materials 43A and 43B having a high melting point filling the grooves 42, while the non-magnetic packing material 73 correponds to the glass material 49 having a low melting point packed into the grooves 45. The ferromagnetic metal thin films 74A and 74B formed on the magnetic transducer head correspond to the metal thin films 48A and 48B formed on the inner sides 46 of the grooves 45, while the coil opening 75 corresponds to the coil groove 61.
With the magnetic transducer head of Figure 49 manufactured with the above described process, the planar surface forming the magnetic gap is inclined at an appropriate angle with respect to the planar surface of the ferromagnetic metal thin films 74A and 74B, which are formed only in the vicinity of the magnetic gap, thus affording the properties of the magnetic transducer head comparable to those of the magnetic transducer head shown in Figure 31.
Since the magnetic gap g is formed only by the metal thin films 74A and 74B, the head is improved in output and compatible with metal tapes.
The metal thin film 74A is formed on a continuous planar surface comprising the side 70A of the projecting portion of the core element 70 and a side of the non-magnetic material 72A, whereas the metal thin film 74B is formed on a continuous planar surface consisting of the side 71A of the projecting portion of the core element 71 and a side of the non-magnetic material 72B. The result is that the metal thin films 74A and 74B are of uniform film structure throughout and exhibit high magnetic permeability in the direction of the path of magnetic flux so that an improvement is achieved in the recording characteristics and playback output of the transducer head.
In the preceding embodiment, the lines a-a, a'-a' along which the composite block shown in Figure 39 is sliced are at right angles with the abutting surfaces of the substrates 20 and 30. It is, however, possible to slice the block in a direction other than the right angle for providing a magnetic transducer head for azimuth recording. It is also possible in the present embodiment to slice the block shown in Figure 48 in an inclined direction with respect to the abutting surfaces of the substrates 40 and 60 instead of along lines A-A, A'-A' or at right angles with said abutting surfaces for similarly producing magnetic transducer heads for azimuth recording.
With the magnetic transducer heads shown in Figures 14,31 and 49, grooves formed on the substrate of ferromagnetic oxides are previously packed with glass, and second grooves are formed in the neighbourhood of the first grooves for forming inclined planar surfaces on which to form ferromagnetic metal thin films. The result is that the magnetic properties of the head are uniform not only in the film portions adjacent to the magnetic gap but in the film portions on the sides of the projecting substrate portion and the ferromagnetic oxides are not exposed on the magnetic gap portion.
When used with high coercive force magnetic tape such as metal tape,the embodiments of magnetic transducer head according to the present invention were found to have a playback output higher by about 3 dB in the frequency range of 1 to 5 MHz as compared to the experimental values obtained with the conventional magnetic transducer head such as shown in Figure 11 wherein the ferrite is exposed in the gap portion for a length equal to for example 40 percent of the track width. The magnetic transducer head may be manufactured with lesser dimensional fluctuations than in the case of the previously proposed magnetic transducer head shown in Figure 3 and was found to have a playback output higher by about 3 dB than that of this transducer head.
The Ni-Zn ferrite, for example, may be used in place of the Mn-Zn ferrite as the ferromagnetic oxide forming the core elements. Permalloy or amorphous alloys may be used in place of Fe-Al-Si alloys as the high permeability magnetic material forming the ferromagnetic metal thin film, as discussed hereinabove.
In using amorphous alloys, uniform film properties of the ferromagnetic metal thin film is impaired by magnetic anisotropy. The metal thin film may have uniform magnetic properties throughout by forming the thin film on a sole planar surface.
The ferromagnetic metal thin film may be advantageously composed of one or more layers.
It will be appreciated from the foregoing that the embodiments of magnetic transducer head are composed of two core elements formed of ferromagnetic oxides, and the ferromagnetic metal thin films are deposited by physical vapour deposition in proximity to the junction surface of the core elements so that the general plane of these metal thin films is inclined at an angle with respect to the junction surface of the core elements which later forms the magnetic gap surface. The magnetic gap is formed solely by the metal thin films which are formed on a common planar surface.
Hence, when forming the metal thin films, there is no necessity of providing a film thickness corresponding to the track width and the transducer head may be mass produced within a shorter time.
The major portion of the contact surface with the tape is formed of ferromagnetic oxides so that the head has superior wear resistance.
The magnetic gap is formed only of the metal thin film so that the head is high in output and compatible with the high coercive tape such as metal tape.
The metal thin film is formed on one planar surface and hence is uniform in film structure throughout, while the metal thin film as a whole exhibits high magnetic permeability in the direction of the path of magnetic flux. Hence, the magnetic transducer head is extremely reliable in operation and has a high recording characteristic and playback output.
The magnetic transducer head is so constructed that the magnetic gap is at the centre of the head chip and surrounded on both sides with nonmagnetic materials for avoiding local wear of the head.
The ferromagnetic metal thin films forming the magnetic gap are formed on a straight line when seen on the contact surface with the tape so that the ferromagnetic metal thin films are not in opposition to each other in other locations than the magnetic gap. The result is the reduced cross-talk in the long wavelength range. The cross-talk may be further lowered by changing the groove profile with respect to the core elements.
The uniform magnetic properties may be assured by the unidirectional growth of the columnar structure of the ferromagnetic metal thin films when seen on the contact surface with the tape.

Claims (43)

1. A magnetic transducer head comprising: a first magnetic core element; and a second magnetic core element; each of said first and second core elements comprising a magnetic ferrite block and a magnetic metal thin film integrated with said magnetic ferrite block; each of said first and second core elements having a first planar surface and a second planar surface; said magnetic metal thin film being provided on said second planar surface and facing an edge thereof to said first planar surface, said second planar surface being inclined with respect to said first planar surface; and said first and second core element being bonded together in such manner that an operating magnetic gap is formed between said edge of said magnetic metal thin film on said first core element and said edge of said magnetic metal thin film on said second core element, said magnetic metal thin film on said first core element and said magnetic thin film on said second core element are in one common plane, and a common contact surface to face a travelling magnetic recording medium is formed by said first and second core elements.
2. A magnetic transducer head comprising: a first and a second magnetic core element bonded together and having an operating magnetic gap between first surfaces of each of said magnetic core elements and a contact surface to face a travelling magnetic recording medium, said gap extending substantially perpendicular to said contact surface forming a depth of said operating magnetic gap; each of said magnetic core elements being formed of a magnetic ferrite block, and a magnetic metal thin film formed on a second surface of said magnetic ferrite block;; said magnetic metal thin film being provided in such manner that an edge of said magnetic metal thin film appearing on said first surface of said magnetic core element extends parallel to a direction of said depth, and another edge appearing on said contact surface extends along a line having an angle not equal to a right angle to said operating magnetic gap as viewed on said contact surface; and said core elements being bonded together in such manner that said operating magnetic gap is formed between said edges appearing on said first surface of each of said magnetic core elements, and said other edges align in a common straight line.
3. A magnetic transducer head according to claim 1 or claim 2 wherein said operating magnetic gap is provided at the central portion of said contact surface.
4. A magnetic transducer head according to claim 1 or claim 2 wherein an angle of said first planar surface and said second planar surface as viewed on said contact surface is between 20 and 80 .
5. A magnetic transducer head according to claim 1 or claim 2 further comprising an opening for a winding coil provided on at least one of said core elements facing said first planar surface dividing said operating magnetic gap and a back gap, and a coil wound through said opening.
6. A magnetic transducer head according to claim 5 wherein said magnetic metal thin film is provided to extend to said back gap.
7. A magnetic transducer head according to claim 5 wherein said back gap is formed between each of said ferrite blocks of said core element.
8. A magnetic transducer head according to claim 1 or claim 2 wherein said magnetic metal thin film has a substantially uniform columnar structure over the entire area of said magnetic metal thin film.
9. A magnetic transducer head according to claim 1 or claim 2 wherein said magnetic metal thin film is crystalline alloy.
10. A magnetic transducer head according to claim 1 or claim 2 wherein said magnetic metal thin film is Fe-Al-Si alloy.
11. A magnetic transducer head according to claim 1 or claim 2 wherein said magnetic metal thin film has substantially uniform characteristics of magnetic anistropy over the entire area of said magnetic metal thin film.
12. A magnetic transducer head according to claim 1 or claim 2 wherein said magnetic metal thin film is amorphous alloy.
13. A magnetic transducer head according to claim 1 or claim 2 wherein said magnetic metal thin film is metal-metalloid amorphous alloy.
14. A magnetic transducer head according to claim 1 or claim 2 wherein said magnetic metal thin film is metal-metal amorphous alloy.
15. 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 on said second planar surface extending from said 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 cut-out portion extending from said first planar surface adjacent to said magnetic metal thin film, said contact surface and another surface extending adjacent to said first planar surface and said contact surface; 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.
16. A magnetic transducer head according to claim 15 wherein said operating magnetic gap is provided at the central portion of said contact surface.
17. A magnetic transducer head according to claim 15 wherein an angle of said first planar surface and said second planar surface as viewed on said contact surface is between 20 and 80 .
18. A magnetic transducer head according to claim 15 further comprising an opening for a winding coil provided on at least one of said core elements facing said first planar surface dividing said operting magnetic gap and a back gap, and a coil wound through said opening.
19. A magnetic transducer head according to claim 18 wherein said magnetic metal thin film is provided to extent to said back gap.
20. A magnetic transducer head according to claim 18 wherein said back gap is formed between each of said ferrite blocks of said core element.
21. A magnetic transducer head according to claim 15 wherein said magnetic metal thin film has a substantially uniform columnar structure over the entire area of said magnetic metal thin film.
22. A magnetic transducer head according to claim 15 wherein said magnetic metal thin film is crystalline alloy.
23. A magnetic transducer head according to claim 15 wherein said magnetic-metal thin film is Fe-Al-Si alloy.
24. A magnetic transducer head according to claim 15 wherein said magnetic metal thin film has substantially uniform characteristics of magnetic anisotropy over the entire area of said magnetic metal thin film.
25. A magnetic transducer head according to claim 15 wherein said magnetic metal thin film is amorphous alloy.
26. A magnetic transducer head according to claim 15 wherein said magnetic metal thin film is metal-metalloid amorphous alloy.
27. A magnetic transducer head according to claim 15 wherein said magnetic metal thin film is metal-metal amorphous alloy.
28. A magnetic transducer head according to claim 15 wherein said non-magnetic material portion is formed of non-magnetic material portion is formed of non-magnetic glass having a first melting point.
29. A magnetic transducer head according to claim 28 wherein said cut-out portion is filled with non-magnetic material.
30. A magnetic transducer head according to claim 29 wherein said non-magnetic material is non-magnetic glass having a melting point lower than said first melting point.
31. A magnetic transducer head according to claim 15 wherein said cut-out portion has a bulged portion towards said magnetic metal thin film.
32. A magnetic transducer head comprising: a pair of magnetic core elements bonded to form an operating magnetic gap therebetween and forming a contact surface for a travelling magnetic recording medium; said operating magnetic gap being formed between magnetic metal thin films each formed in said magnetic core elements and said magnetic metal thin films extending on said contact surface along a straight line having an angle not equal to a right angle to said operating magnetic gap; said magnetic metal thin films having substantially uniform columnar grain structure over the entire area of said magnetic metal thin films.
33. A magnetic transducer head according to claim 32 wherein said magnetic metal thin film is crystalline alloy.
34. A magnetic transducer head according to claim 32 wherein said magnetic metal thin film is Fe-Al-Si alloy.
35. A magnetic transducer head comprising: a pair of magnetic core elements, being bonded to form an operating magnetic gap therebetween and forming a contact surface for a travelling magnetic recording medium; said operating magnetic gap being formed between magnetic metal thin films each formed in said magnetic core elements, and said magnetic metal thin films extending on said contact surface along a straight line having an angle not equal to a right angle to said operating magnetic gap; said magnetic metal thin film having substantially uniform characteristics of magnetic anisotropy over the entire area of said magnetic metal thin film.
36. A magnetic transducer head according to claim 35 wherein said magnetic metal thin film is amorphous alloy.
37. A magnetic transducer head according to claim 35 wherein said magnetic metal thin film is metal-metalloid amorphous alloy.
38. A magnetic transducer head according to claim 35 wherein said magnetic metal thin film is metal-metal amorphous alloy.
39. A method of manufacturing a magnetic transducer head comprising the steps of: preparing a pair of magnetic ferrite blocks each having a first and a second surface adjacent to each other; forming a first groove over a corner of said first and said second surface extending to said first and second surfaces; forming a second groove over said corner and adjacent to said first groove, said second groove having a third surface adjacent to said first groove and extending slantingly with respect to said second surface, a line formed by said second surface and said third surface being extended perpendicular to said first surface; forming magnetic metal thin film over said surface by physical vapour deposition; polishing a side of said second surface to expose an edge of said magnetic metal thin film; forming a third groove for winding a coil on at least one of said ferrite blocks; and bonding said ferrite blocks to form a magnetic gap between said edges of said magnetic metal thin film formed on said ferrite blocks.
40. A method according to claim 39 further comprising the step of filling said first groove with non-magnetic material.
41. A method according to claim 39 further comprising the step of filling said second groove with non-magnetic material.
42. A method according to claim 41 wherein a step of filling non-magnetic material in said second groove and a step of bonding said ferrite blocks to form a magnetic gap between said edges of said magnetic metal thin film formed on said ferrite blocks are carried out at the same time.
43. A magnetic transducer head according to any one of the embodiments or modified embodiments hereinbefore described with reference to Figures 14 to 49.
GB08432443A 1983-12-30 1984-12-21 Magnetic transducer heads Expired GB2153581B (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP58250988A JPS60229210A (en) 1983-12-30 1983-12-30 Magnetic head
JP59078242A JPS60223012A (en) 1984-04-18 1984-04-18 Magnetic head
JP9975184A JPS60243810A (en) 1984-05-18 1984-05-18 Magnetic head

Publications (3)

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GB8432443D0 GB8432443D0 (en) 1985-02-06
GB2153581A true GB2153581A (en) 1985-08-21
GB2153581B GB2153581B (en) 1988-05-25

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AT (1) AT393566B (en)
AU (1) AU582736B2 (en)
CA (1) CA1236212A (en)
DE (1) DE3447700A1 (en)
FR (1) FR2558000B1 (en)
GB (1) GB2153581B (en)
IT (1) IT1182707B (en)
NL (1) NL194772C (en)

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GB2167597A (en) * 1984-11-26 1986-05-29 Sony Corp Magnetic transducer heads and methods of making such heads
US4704788A (en) * 1985-11-29 1987-11-10 Grundig E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig Helland, Stiftung & Co. Kg Method for making magnetic heads
GB2268309A (en) * 1992-06-16 1994-01-05 Samsung Electro Mech Composite magnetic head

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JPH0654528B2 (en) * 1986-04-23 1994-07-20 株式会社日立製作所 Magnetic head
JPS62266712A (en) * 1986-05-14 1987-11-19 Mitsubishi Electric Corp Composite magnetic head
CN1012113B (en) * 1986-05-21 1991-03-20 菲利浦光灯制造公司 Magnetic transducing head having clad core faces
JPS6370912A (en) * 1986-09-12 1988-03-31 Hitachi Ltd Glass for joining magnetic head gap
JPS63146202A (en) * 1986-12-09 1988-06-18 Canon Electronics Inc Magnetic head and its production
JP2513205B2 (en) * 1987-02-04 1996-07-03 ソニー株式会社 Composite magnetic head

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2167597A (en) * 1984-11-26 1986-05-29 Sony Corp Magnetic transducer heads and methods of making such heads
US4704788A (en) * 1985-11-29 1987-11-10 Grundig E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig Helland, Stiftung & Co. Kg Method for making magnetic heads
GB2268309A (en) * 1992-06-16 1994-01-05 Samsung Electro Mech Composite magnetic head
GB2268309B (en) * 1992-06-16 1996-09-11 Samsung Electro Mech Composite magnetic head

Also Published As

Publication number Publication date
IT8449363A0 (en) 1984-12-27
DE3447700C2 (en) 1993-02-18
IT1182707B (en) 1987-10-05
AU3707484A (en) 1985-07-04
ATA412784A (en) 1991-04-15
CA1236212A (en) 1988-05-03
GB8432443D0 (en) 1985-02-06
IT8449363A1 (en) 1986-06-27
NL8403971A (en) 1985-07-16
GB2153581B (en) 1988-05-25
FR2558000B1 (en) 1994-02-25
DE3447700A1 (en) 1985-07-25
NL194772B (en) 2002-10-01
AU582736B2 (en) 1989-04-13
FR2558000A1 (en) 1985-07-12
AT393566B (en) 1991-11-11
NL194772C (en) 2003-02-04

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