JPS62183012A - Magnetic head and its manufacture - Google Patents

Abstract

PURPOSE:To suppress decomposition and a crack due to processing of a ferromagnetic metallic film caused by the machine processing by adopting a composite material magnetic core being the combination of a magnetic core made of an oxide magnetic material and a tip chip member imbedded with a ferromagnetic metallic film. CONSTITUTION:A magnetic core 30 of a ferromagnetic oxide magnetic substance of a high specific resistance made of an Mn-Zn single crystal ferrite is used as the major component of a magnetic circuit. A tip chip member 31 is adhered onto the magnetic core 30 by an adhesives 32. The tip chip member 31 is a separate member from the magnetic core 30 and adhered during the head manufacture process. The member 31 is formed by sandwiching a ferromagnetic metallic film 35 made of a Sendust film at the midpoint in the track width direction of side cores 33, 34 made of an oxide comprising an Mn-Zn single crystal ferrite. The member 31 having a sandwich structure of the cores 33, 34 and the film 35 in the track broadwise direction has a thickness (t) in the gap depth direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application The present invention relates to magnetic heads and the like used in video tape recorders (hereinafter abbreviated as VTR) suitable for recording and reproducing on high coercive force media such as metal tapes. It relates to its manufacturing method.

2. Description of the Related Art In general VTRs, oxide magnetic materials such as single crystal ferrite are often used as the core material of the magnetic head. However, in recent years, with the advancement of high-density recording and reproducing technology, magnetic heads for VTRs are required to be capable of recording on and reproducing magnetic tapes with high coercive force such as metal tapes, and to have narrower gaps and narrower tracks. . To meet this requirement, oxide magnetic materials with low saturation magnetic flux density are not suitable as magnetic head core materials. As a head compatible with narrow-gap, narrow-trunk metal tapes, the magnetic core is made of a composite magnetic material consisting of an oxide magnetic material such as single-crystal ferrite and a ferromagnetic metal material such as sendust or amorphous alloy, which has a high saturation magnetic flux density. Many magnetic head structures have been proposed in which half pairs of magnetic cores are joined via a gap spacer made of glass or the like. As a typical example of this conventional composite structure, FIGS. 5(a) and 5(b) are perspective views and x-x'
A line cross-sectional view is shown. Figure 5 shows a configuration in which a ferromagnetic metal material exhibiting a high saturation magnetic flux density, such as sendust, is attached to the front gap of the half-dormant pair of magnetic cores, which is most likely to cause magnetic saturation during recording, and 1 and 2 are C-type, respectively. This is a type 1 ferrite core half. Ferromagnetic metal films 3, 4 made of sendust or amorphous alloy, having a thickness of 1Q to 20 μm, are deposited on opposing faces of the core halves 1.2 by sputtering or the like. Furthermore, grooves are formed in each of the core halves 1 and 2 to regulate the track width of a sliding surface 5 of a magnetic tape (not shown). Core half 1 has groove 6
, 7. The core half body 2 has grooves 8 and 9, each of which is filled with high melting point glass and shaped into a predetermined shape. Furthermore, the core half 1 is provided with a winding window 1Q for a winding coil (not shown). This winding 10 regulates the lower end of the gap depth of the magnetic head. Next, either one of the semi-dead cores has grooves 6, 7 on one or both of the abutting opposing surfaces.
A glass having a lower melting point than the glass material used for filling the gap spacer 11 is sputtered to form the gap spacer 11, and after the core halves 1 and 2 are butted together, pressure welding is performed. At this time, the thickness of the gap spacer 11 is adjusted so that the core halves 1 and 2 are bonded together and at the same time the desired front gear sawing length is achieved.

As a final finishing step, the surface of the magnetic tape sliding surface 6 is polished and a desired gap depth is formed. Note that the track width regulating grooves 6, 7, 8.9 on the magnetic tape sliding surface 6
The step of filling the glass material into the gap spacer 11 can also be carried out when the semi-dead core 1.degree. 2 is welded under pressure and heat after the gap spacer 11 is formed.

FIG. 6 shows a perspective view of another conventional example. The magnetic head half-dead core blocks 12 and 13 are joined with a gap spacer 14 in between. Each half-break core block 12.1
3 is a ferromagnetic metal film 17.1 made of sendust, amorphous alloy, etc. on a non-magnetic substrate 15.16 made of glass, ceramic, etc.
8 is sputtered to a thickness corresponding to the desired track width.

In consideration of high frequency characteristics, magnetic films are generally multilayered with an electrically insulating interlayer film (not shown) interposed therebetween. On top of the ferromagnetic metal films 17 and 18, reinforcing nonmagnetic substrates 19 and 20 made of glass, ceramic, etc. are bonded with resin, glass, or the like. Note that a winding window 21 is open in the half-vacant core block 12.

It is also possible to use a ferromagnetic metal amorphous alloy thin plate having a thickness equivalent to the track width.

In the magnetic head configured as described above, the purpose of using a ferromagnetic metal body having a high saturation magnetic flux density is to reduce magnetic saturation in the front gap of the magnetic core when recording a high coercive force magnetic tape such as a metal tape. This is to prevent it. In the configuration shown in FIG. 5, ferromagnetic metal bodies are disposed only in the front gap of the pair of half-dormant cores 1 and 2 made of ferrite and opposite the pack gap, so that magnetic saturation in the front gap is reduced.

In the configuration shown in Figure 6, the magnetic core as a magnetic flux propagation path is only a thin film or thin plate made of a ferromagnetic metal, and the cross-sectional area of the magnetic path through which the magnetic flux flows is regulated by the thickness of the thin film or thin plate, and this thickness is determined by the magnetic flux. Equal to the track width of the tape sliding surface. However, since all the magnetic path components including the front gap are made of ferromagnetic metal bodies with high saturation magnetic flux density, the magnetic saturation of the core is reduced.

Problems to be Solved by the Invention However, the conventional configuration shown above had several major problems as described below.

First, the configuration shown in FIG. 6 will be described.

(1) During the process of attaching a ferromagnetic metal film such as sendust to the opposing surfaces of each pair of ferrite core halves by vacuum deposition such as sputtering, or during machining of the tape sliding surface,
An altered layer occurs in the ferrite core that joins the ferromagnetic metal film. This deteriorated layer appears as a secondary gap on the tape sliding surface and causes large undulations in the frequency characteristics of the head. As a countermeasure to this, the film thickness of the ferromagnetic metal film was increased by 2
It is necessary to make it significantly thicker, from 0 to 3071m, and to move the secondary gap away from the main front gap.
Considering the film thickness, mass production was lacking.

(2) As a result of increasing the thickness of the ferromagnetic metal film as described above, the ferromagnetic metal film cracks during sputtering or peels off from the ferrite core surface. Moreover, it induces cracking and peeling of the ferromagnetic metal film during machining such as head chip cutting and sliding surface polishing.

(3) If the boundary area between the ferrite and the ferromagnetic metal film is equal to or slightly larger than the front gap constituent area, there is a risk of magnetic saturation of the ferrite core at the boundary. As the demand for narrower tracks becomes stronger, increasing the boundary area requires increasing the thickness of the thin film, which poses problems in mass production when film formation time is taken into account.

(4) As the thickness of the ferromagnetic metal film increases, the eddy current loss increases, leading to deterioration of the high-frequency output of the head.

Next, problems with the configuration shown in FIG. 6 will be described.

(5) When multiple layers of ferromagnetic metal thin films or thin plates are laminated on a non-magnetic substrate via an electrically insulating interlayer film, processing changes occur in each layer of the magnetic film during machining. This altered layer appears on the tape sliding surface.

When a ferromagnetic metal body is sandwiched between two non-magnetic substrates to form a half-core core, the non-magnetic substrate is bonded with a resin or glass material in the subsequent process, but this bond is applied to the tape sliding surface. The layer was exposed, resulting in uneven wear as the tape ran.

(7) Since the ferromagnetic metal body constitutes the entire magnetic core, and the thickness of the magnetic body is the track width, consideration must be given to the processing process and the number of head chips on one board during mass production. This resulted in poor throughput and increased manufacturing costs.

In view of the above-mentioned problems, the present invention provides a composite magnetic core compatible with high coercive force tape made of a composite magnetic material of an oxide magnetic material and a ferromagnetic metal film. This eliminates the influence of the gap that occurs next and the magnetic saturation of the oxide magnetic core by expanding the boundary area between both magnetic materials, improving the uneven wear characteristics of the tape sliding surface, and providing excellent frequency characteristics and mass productivity. The present invention provides a magnetic head having a structure and a method for manufacturing the same.

Means for Solving the Problems The magnetic head of the present invention has a magnetic circuit formed by a magnetic core made of an oxide magnetic material with high specific resistance and a ferromagnetic metal film forming a front gap. is in contact with the magnetic core of the oxide magnetic material with a length determined by its film thickness and the radius of curvature of the magnetic tape sliding surface, and is exposed in the magnetic tape running direction on the magnetic tape sliding surface. . The above-described ferromagnetic metal film extending in the running direction of the front gap portion and the tape sliding surface can be realized by a single thin film lamination process on a substrate that is a separate member from the magnetic core of the oxide magnetic material.

The ferromagnetic metal film exposed on the sliding surface of the magnetic tape, which is used in head manufacturing means, is processed to have the desired regulating track width at the front gap, and most of the part that vibrates with the magnetic tape is within the regulating track width. It has a structure in which it is embedded in an oxide magnetic material or non-magnetic material, which has a wear resistance of 3 to 4 times and has excellent wear resistance.

The oxide magnetic material constitutes the main part of the magnetic core, and the ferromagnetic metal film attached to the front gap prevents magnetic saturation in the front gap and also prevents the tape from running on the tape sliding surface. The ferromagnetic metal film exposed along the tape direction secures the boundary area with the oxide magnetic material, greatly reducing magnetic saturation at the boundary, and at the same time moves the boundary line in the tape running direction away from the main front gap. The secondary gap effect caused by the altered layer of oxide magnetic material can be significantly reduced.

Furthermore, by configuring the ferromagnetic metal film and the magnetic core of the oxide magnetic material as separate members, deterioration of the characteristics of the ferromagnetic metal film due to machining can be prevented, and improved machining accuracy and mass productivity can be realized.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 shows a perspective view of the magnetic head of the present invention, in which a pair of C-type and 1-type magnetic core halves are joined, with the C-type core half being shown by a solid line and the I-type core half being shown by a dotted line. I'm drawing it with The following explanation will mainly be made using the C-type core half-break.

A magnetic core 30 made of an oxide magnetic material having ferromagnetism and high resistivity, such as Mn-Zn single-crystal ferrite, is the main component of the magnetic circuit. A tip end member 31 is placed on the magnetic core 30 with an adhesive 32 made of glass or resin.
are joined with. The distal tip member 31, which is a feature of the present invention, is a separate member from the magnetic core 30, and is joined during the head manufacturing process. The tip tip member 31 is Mn-Z
A ferromagnetic metal film 35 made of a sendust film, an amorphous alloy film, etc. is sandwiched between side cores 33 and 34 of oxide magnetic material or nonmagnetic material made of n-single crystal ferrite or the like in the track width direction. The tip end member 31 has a sandwich structure of side cores 33, 34 and a ferromagnetic metal film 36 in the track width direction.
The opposing surface 37 of the front gap 36 formed with the tip tip member 44 of No. 3 has a thickness t in the gap depth direction, and constitutes a part of the operational gap depth D of the head.

Partially along the tape running direction, the thickness of the tip member 31 becomes thinner as it moves away from the front gap 36, and becomes zero at a distance, forming a boundary 38 with the magnetic core 30.

The width of the ferromagnetic metal film 36 on the tape sliding surface 39 is T, and the track width regulating groove 40 on the front gearing 36
．． 41 to have an effective track width Tw.

The track width regulating groove 40.41 is filled with a high melting point glass material, and a gap spacer 46 is provided on each opposing surface of the magnetic core 43 and the C-shaped magnetic core 30, or on either one of the opposing surfaces to provide a desired front gap length. It is attached. This gap spacer 46 has track width regulating grooves 40, 41.
It is formed from a glass material having a different melting point from the glass material filled in the glass material, and it is necessary to select the above two glass materials depending on the order of the process.

Pressure heat welding is performed on each half core, forming C type and 1 type.
The joining of the mold core is completed.

In the configuration of the embodiment shown in FIG. 1, the gap depth D is formed by the thickness t of the ferromagnetic metal film 36 such as sendust and the magnetic core 30 made of oxide magnetic material. Ferromagnetic metal film 36 exhibiting high saturation magnetic flux density
It can also be composed of This embodiment is shown in FIG.

FIG. 2 shows only the C-type core, and the same parts as in FIG. 1 are given the same numbers. In FIG.
The thickness t of the ferromagnetic metal film 49 in the gap depth direction at the front gap is D', which is the total height of the gap depth, and the length on the tape sliding surface in the tape running direction is L'. It forms a boundary SO with the magnetic core 30.

42 is a winding window. Reference numerals 47 and 49 indicate side cores arranged on both sides of the ferromagnetic metal film 49. 51 and 52 are track width regulating grooves.

In the embodiment described above, the length L or L' of the ferromagnetic metal film embedded in the tip member in the tape running direction is determined by the gap depth formed by the ferromagnetic metal film and the radius of curvature of the head tip. The radius of curvature of the head tip shape is 6rrLr
Assuming that the magnetic core width in the tape running direction is 1wn, L or L' is 0.35 rtan when the thickness of the ferromagnetic metal film t=10μm, and L when t==20μm.
Or L' becomes 0.49 reward. Further, the ferromagnetic metal film formed as a thin film can be multilayered through an electrical feed line interlayer film in consideration of the high frequency characteristics of a video signal of a VTR. FIG. 3 shows that the ferromagnetic metal film 54 of the distal tip member 63 is attached to the three-layer ferromagnetic metal film 54 in the gap depth direction.
2, etc., with interlayer films 66 interposed therebetween to form a gap depth.

Note that the material of the side core constituting the distal tip member is not limited to oxide magnetic materials such as ferrite, but may also be non-magnetic materials such as glass materials and ceramic materials.

Next, an example of the manufacturing process of this embodiment will be described.

FIGS. 4(a) to 4(i) show the manufacturing process. In this step, the side core of the tip member is made of oxide magnetic material. In FIG. 4(a), a plurality of grooves 61 are formed in an oxide magnetic substrate 60 made of single crystal ferrite or the like, which becomes the substrate of the tip end member and acts as a side core. The groove width must be greater than the track width. In FIG. 4(b), a ferromagnetic metal film 6 such as sendust or amorphous alloy is placed on a grooved oxide magnetic substrate 60.
2 is deposited by sputtering method. In Figure 4 (C),
A planarized substrate 63 is manufactured so that the upper surfaces of the ferromagnetic metal films 62 embedded in the plurality of grooves 61 are on the same plane. Care must be taken so that the ferromagnetic metal film 62 does not remain on the surface of the convex portion of the oxide magnetic substrate 60. In FIG. 4(d), a flattened substrate 63 is placed on a base material block 64 of an oxide magnetic material such as single crystal ferrite, which becomes the magnetic core of the main component of the magnetic path, and the upper surface of the ferromagnetic metal film 62 is oxidized. A head block 65 is made by joining the head block 65 so as to face the magnetic material base material block 64. Further, a dashed line A- which divides the longitudinal direction of the ferromagnetic metal film 62 into two equal parts.
Cut into 2 blocks along A. In Figure 4(e),
Each half-block cut into two halves is machined with a track width regulating groove 66 and a glass material installation groove 67 for filling with a high melting point glass material. 68 is a glass rod.

In FIG. 4(f), a glass rod 6 is heated using a high-temperature heat treatment furnace.
8 is melted and glass material e9 is poured into the track width regulating groove 66. The I-shaped core 70 is completed by shaping and grinding the half body block to the desired dimensions. On the other hand, in the process shown in FIG. 4(J), the C-type core 71 is completed by forming a groove 72 for a winding window in the I-type core 70. When processing the groove 72, the desired gap depth and Adjust the dimension δ from the magnetic film to the top end of the groove so that Glass rod 7 for adhering both cores by sputtering etc.
4 is inserted into the winding window groove 72 and bonded by pressure and heat to complete the bonding. After joining the above core pair, gap depth coarse grinding is performed to line E-E, and B-B with azimuth angle θ,
B'-B'.

Make the cut along B''-B'' and height shaping line C-C. The tape sliding surface of the head core chip (two chips are completed in the above example) is polished to a circular arc shape with the desired radius of curvature as shown in Fig. 4(i), and then the tape sliding surface is polished to a circular arc shape as shown in Figs. 1 and 2. A head core chip 76 having the same configuration as the one above is completed.

The operation of the magnetic head constructed as described above will be explained below mainly with reference to FIG.

The tip tip member 31 on the magnetic core, which is a main component of the magnetic circuit, constructs the vicinity of the front gap 36 where magnetic saturation is most likely to occur during recording, thereby forming a magnetic core made of a composite magnetic material. The induced magnetic flux induced by the recording current flowing in the coil (not shown) wound around the winding window 42 is caused by the magnetic core 3o → the ferromagnetic metal film 36 → the front gap 36 → the tip tip member 44 of the I-shaped core. The magnetic flux flows along the magnetic flux propagation path from the ferromagnetic metal film (not shown) to the magnetic core 43 to the magnetic core 30, and a signal is recorded on the magnetic tape by leakage magnetic flux at the front gap 3e. The front gap magnetic field required for high-density saturation recording on magnetic tape is said to be 4 to 6 times more than the coercive force of the magnetic tape, although it also depends on the gap length and gap depth. Since the ferromagnetic metal film 36 has a high saturation magnetic flux density, magnetic saturation at the front gap can be suppressed even during saturation recording on a metal tape having a coercive force of approximately 1600 oersteds. Furthermore, since the junction area between the magnetic core 3o, which has a low saturation magnetic flux density, and the ferromagnetic metal film 35 is increased in the magnetic flux propagation path, magnetic saturation of the magnetic core 30 near the junction boundary is prevented. The width T of the ferromagnetic metal film 36 can be adjusted to determine the junction area necessary for design. Also, on the sliding surface of the magnetic tape, the boundary 3 between the ferromagnetic metal film 35 and the magnetic core 30
8 appears, but according to this configuration, L or L' is 0.36.
~0.5- and away from the front gap 36, spacing with the magnetic tape occurs, and the deterioration of the recording/reproducing characteristics caused by the secondary gap disappears. Furthermore, by making the ferromagnetic metal film 64 multi-layered with the insulating interlayer film 55 to a thickness of about 1000 as shown in FIG. This reduces the deterioration of Furthermore, in the groove formation example shown in FIG. 2, if the entire height of the gear lug depth on the front gap surface is made of a ferromagnetic metal film, the magnetic saturation margin of the front gap will further increase, and the area of contact with the magnetic core 30 will also increase. be able to.

As described above, according to this embodiment, by constructing the tip tip member in which the ferromagnetic metal film is embedded on the magnetic core of the oxide magnetic material, which is the main component of the magnetic circuit, it is possible to sandwich the gap spacer. Magnetic saturation in the front gap between the opposing C-type and 1-type cores is prevented, and since the boundary area between the magnetic core and the ferromagnetic metal film is increased, magnetic saturation near the boundary can also be eliminated. Furthermore, the influence of the gap due to the tip tip member and the deterioration of high frequency output can be significantly reduced. Furthermore, according to the manufacturing process shown in this example, a groove is formed on the substrate that will become the tip tip member, a ferromagnetic metal film is embedded in the groove, and the film is bonded to the base material block of the magnetic core so that the surfaces thereof are in contact with each other. are doing. This means that there is extremely little exposure of the ferromagnetic metal film during tape sliding surface polishing and gap depth processing to complete the Herad chip. Therefore, the ferromagnetic metal film deteriorates due to machining and peels from the substrate.

It is also very effective in removing problems such as cracks. There is a large degree of freedom in selecting the substrate material that will become the tip member, and when considering the uneven wear characteristics of the tape sliding surface, there is a wide range of selection of substrate materials that have the same hardness as the ferromagnetic metal film.

Effects of the Invention The present invention provides a composite material that is a complete combination of a magnetic core made of an oxide magnetic material and a tip tip member embedded with a ferromagnetic metal film that extends long along the magnetic tape running direction on the front gap side and tape sliding surface. By using a magnetic core, it is possible to prevent magnetic saturation of the oxide magnetic material near the front gap portion of the C-type and 1-type cores, which face each other with the gap spacer in between, and the boundary between the ferromagnetic metal film and the ferromagnetic metal film. By configuring the magnetic core as a separate member, there is greater freedom in substrate selection during the manufacturing process of advanced chip components, and by embedding a ferromagnetic metal film after groove processing, the substrate surface can be flattened at the level of the ferromagnetic metal film thickness. Since the ferromagnetic metal film is bonded to the base material block of the magnetic core through a chemical treatment, there is no need to expose the ferromagnetic metal film during cutting when finishing the head chip or lapping the tape sliding surface. It is possible to realize a narrow track width, narrow gap magnetic head that is mass-producible, has excellent wear resistance, and has excellent frequency characteristics, such as suppressing processing deterioration of the metal film, cracking, and peeling from the substrate.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a magnetic head according to a first embodiment of the present invention, FIG. 2 is a perspective view of a C-shaped magnetic core according to a second embodiment of the present invention, and FIG. 3 is a perspective view of a magnetic head according to a third embodiment of the present invention. A perspective view of a C-shaped magnetic core in an embodiment, and FIGS.
a) is a perspective view of a conventional magnetic head, and FIG.
FIG. 6 is a cross-sectional view taken along the line xx' in FIG. 6(a) and a perspective view of another conventional magnetic head. 30.43...Magnetic core, 31,44,46°63...Tip tip member, 33,34,47.
48... Side core, 35, 49, 54.62
...Ferromagnetic metal film, 36...Front gap, 37...Front gap opposing surface,
38...Boundary, 39...Magnetic tape sliding surface, 40, 41.61.52゜66...Track width regulation groove, 42...Volume Line window, 46°73・
...Gap spacer, 6o...Substrate,
61... Groove, 63... Flattened substrate, 6
4...Magnetic core base material block, 66...
・Head block, 70...Air core, 71・
...C-shaped core, 72 ... Winding window groove, 7
6...Head core chip. Name of agent: Patent attorney Toshio Nakao and 1 other person30
Sweat 3 - - f Magnetic - Core 3i Oblique - - Tip brittle 97 - Evil ^ Ya 33, 34 - 11 Void core gar - 5 pull (Near + Raw μ Moon Shaku 3tE - - 711 Toiyano 7゜ Fig. 1 37- ・ Light facing surface 38- Boko 42- Injuki 45---(〒〒〒〒7°Swi-7 ffi4Figure 4

Claims (7)

[Claims] (1) A magnetic circuit is formed by a magnetic core made of an oxide magnetic material and a ferromagnetic metal film forming a front gap, and the ferromagnetic metal film has a curvature of the ferromagnetic metal film thickness and a magnetic tape sliding surface. The magnetic head is exposed in the magnetic tape running direction on the magnetic tape sliding surface with a length determined by the radius, and is in contact with the magnetic core. (2) A magnetic head according to claim 1, wherein the ferromagnetic metal film and the magnetic core made of an oxide magnetic material are each constructed from separate members. (3) A magnetic head according to claim 1, wherein the ferromagnetic metal film is multilayered with an electrically insulating interlayer film interposed therebetween. (4) The ferromagnetic metal film is deposited by sputtering or the like on a substrate made of an oxide magnetic material or non-magnetic material having a groove deeper than this film thickness, and the surface of the ferromagnetic metal film formed in the groove is The surface of the substrate is flattened so that it is flush with the surface of the substrate, and the flattened surface is joined to the base material block of the magnetic core made of oxide magnetic material to form a head block, and then the head block is formed. Cutting the head block into two equal parts in the longitudinal direction of the ferromagnetic metal film,
A method of manufacturing a magnetic head, characterized in that the magnetic head is processed into C-type and I-type magnetic cores, respectively. (5) Claim 4, characterized in that the groove width formed on the substrate made of oxide magnetic material or non-magnetic material is greater than or equal to the track width and smaller than the magnetic head width in the track width direction. A method of manufacturing the described magnetic head. (6) A magnetic device according to claim 4, characterized in that the length of the groove formed on the substrate made of an oxide magnetic material or a non-magnetic material is greater than or equal to the width of the magnetic head in the magnetic tape running direction. Head manufacturing method. (7) A method of manufacturing a magnetic head according to claim 4, wherein the ferromagnetic metal film is multilayered with an electrically insulating interlayer film interposed therebetween.